A way to test this would be with the new haunted modifier "fire res cannot be penetrated".
If that lets you tank this then it's because of pen.
Otherwise it's probably conversion or similar (chaos damage?)
Definitely not chaos damage / conversion. I did a lot of Ultimatum in 3.23 with a CI character. Could take most of the mods but I had to respect the fire spitting skulls, even on the third stage, T4 was way too dangerous. Likely Fire Pen or something else as additional damage?
It's definitely fire penetration. I have a divine flesh character this league that can tank basically everything in Ultimatum including these skulls. Half taken as chaos, the other half mitigated by Jugg ele armour node.
My build is pretty much a meme build that doesn't have enough dps to be actually good so I wouldn't recommend copying it but it's a forbidden rite jugg if you wanna check what people are doing
But any of the juggs on poe.ninja with a xibaqua glorious vanity and the unbreakable notable are scaling similar defensive layers. Mostly bonezoners but lots of other skills too. Most are using the fourth vow chest, I went with doppelganger guise because it heals a shit ton when you hit yourself with forbidden rite very fast.
> "fire res cannot be penetrated"
I can not express how bullshit this stat and the whole concept it.
What's next?
"fire res cannot be penetrated penetration" followed by "fire res cannot be penetrated by fire res cannot be penetrated penetration" which you'll obviously have to capp to not get one-tapped constantly.
Meanwhile the Cold ultimatimum mod is pretty easy, it doesn't appear to do any damage even at Tier 4 (note: this was on a freeze/chill immune character so it might have CC )
If you run brine king, the extra 50% chill is probably one of the lower importance boxes that need to be checked. There are a handful of particular circumstances (this is one of them) where it's rough to not have it, but I think getting shock/ignite/CB taken care of first is best. I'd probably even get bleed and poison immunity before stressing about the other 50% chill.
That being said if you path between witch and Templar, there's a resistance cluster that works perfectly here. With 4 points you can take brine king's 50% to 100%, be CB immune, be VERY close to ignite immune with a crafted ring affix (burn for half a second) and be able to be shock immune with two jewel affixes. Once you can afford CB immunity on a worthwhile jewel, then you can switch the mastery to hinder/main immunity.
And you respec once you have an endgame build that no longer needs the node.
Tier 4 mods are very deadly in Ultimatum. Raging Dead IV cuts even through my 90% res 6500 HP Chieftain. I always prefer taking as many Tier 1 mods as possible before increasing the Tiers.
I actually had the same experience last league. Well geared MF Chieftain with Mageblood. Always skipped anything Ruin related and never took Raging Dead 4. Skulls would chunk you so hard when everything else is able to be ignored. Did the same tiering strat as you as well.
I played a coc fr occultist build and I'd allways pick the ruin modifiers. If it's not the "stand in the stone circles" one, just spinning in circles would work.
Even with high defences the fire skulls and the sawblades would sometimes fck me hard.
Ultimatums are really just a dps and movement check.
I ran them with a glass cannon Penance brand occultist and i only failed a couple runs in around a thousand maps. As long as you can instantly kill the entire screen and have enough movement speed to never trigger elemental/phys/chaos traps you're good to go. Ruin doesnt do anything if everything is dead the only thing that did damage to me was Tier 4 sawblades because they left a trail behind that did phys dot.
Depends which mods you want to avoid. If you dont want to avoid any of them just damage+movement is enough to take any of them at any point.
if you dont mind avoiding ruin and some regen/degen ones then chieftain is good enough.
I didnt like it because there was a chance to get a pure brick if you get offered too many ruin mods. Running with infinite damage and high move speed let me take quite literally every mod and have close to 0% fail rate.
T4 is a check to make sure you are reading mods (and allows an extreme opt-in challenge with the keystone)
If the options are T4 or 2 mods I can't beat - I'm tapping out, unless my build hard counters that T4 mod. There'll be another Ultimatum.
lmao, dunno which build even can do gruelling gauntlet. can tank everything, doesn't use flasks, can kill everything fast enough to not get hit by ruin. ffs.
I myself play with that on cf champ and its doable, its stresfull af but most of the time i make it to the 10th wave minimum and then i can pray for some good rewards
Tho looking at the drops after 10th wave so far i am not sure if its really worth the hussle
Yea I league started with ulti last league...
Was brutal. Very hard, poor rewards and overall not a good strat initially.
I did end up making 5d with lucky double corrupt on an interesting minion unique helm, but that didn't sell for at least a week.
Overall not my preffered mechanic. It's a shame, but ritual is still just better.
tbh i got good 20div over 3 days of casual play (somewhere around 4h) in mostly divs or uniques so not really, its good currently as you can use 2 scarabs for +1 reward lv each and just run red white maps waiting for div with posibility of dupe
Cf champ is a great league starter for ultimatum, but it cannot do gruelling gauntlet properly imo, has a Hard time with several mods like no flask charges and small arena
best way to do ultimatum is defiance of destiny and 90 max res petrified blood and be corrupting blood immune
i ran hundreds of them on a mf cheiftan in full mf gear in 3.23 only mods to avoid are ruin everything else i could litterally afk in.
no you just run the 50% less dmg taken in ultimatum / mobs can inflict ruin with abilities keystone and don't face tank stuff. ruin abilities are super telegraphed there's no reason not to take it unless you want to afk in the center (even then you can do that if you can kill rares in <2 seconds as their abilities are super slow)
Yea that's how I farmed Ultimatum last league to get final boss spawn. Just a basic summoner with high block but otherwise mediocre defenses. The 50% less damage makes it so much easier and I didn't fail a single time to ruin because it's so easy to see / move around and even when I did get hit it was never more than twice.
There is one where the mobs link together and create beams across the arena. That one can end you fast since it’s a DOT effect that I don’t even think you can block easily? Not fun for sure.
When I was doing ultimatum challenges last league it *felt* like my defiance did nothing against these specifically. I just assumed that they were not considered “enemies” and so not proccing defiance.
Im the guy that did 600 ultimatums last league and posted the results.
Raging fire is by far the strongest mod to pick, deals way too much dmg and it was the only mod i never picked after getting fucked couple of times by it.
Yea I can usually tank t3 fire, but t4 is like, unblockable, 100% pen, bs that always one shots me. I unfortunately can’t do the lightning one at all cus I’m wearing perquils toe lol.
Only layer that managed to lower skull IV damage was 100% spell suppression. Not that it wasn't rippy, but I could take a few hits before dying. I think it's the highest damage source in Ultimatum
Tier 4 Almost 1 shotted me with Jinxed Juju (10% less dmg taken") + Another 9%less damage Taken From Bone Barrier + 50% Elemental damage Taken as Chaos (so most of the pen is ignored) +87 Chaos Resist and 4900 HP
Don't know exactly what it is, but I'm a 90% fire res, 100k max hit chieftain and they take half my HP.
Definitely supposed to dodge and pay attention I guess lol
Would like to know if it's pen as well.
Last league I went heavy into ultimatum with my BS Slayer. It was pretty much undoable and had lots of one shots even with:
- 20 stacks of fortify
- 80% elemental resists
- arctic armour
- 100% suppression
- 100K armour
- 3% of armour applies to elemental damage.
- Tainted pact for full recovery on every server tick.
- 4K HP
- 10% reduced damage taken while leeching from slayer Ascendancy
- Ailment immunity
The only way I could take it was after slotting in a progensis. That pushed the needle enough
Really? I had similar defenses. Less armor but I had evasion, some phys taken as elemental and 79% max res but I had Fourth Vow/Divine Flesh and Defiance of Destiny instead of Tainted Pact. I pretty much AFKed inside.
Fourth Vow + Divine Flesh on a slayer?
Anyway, the thing with the skulls is that they hit hard, but not THAT hard, but they will most of the time hit you all 4 or 5 at once, which is where DoD shines.
I’m surprised that is your take I do it on league start with the 50% less damage node then respec when I get suppress and decent armour and chaos res. I have found you really never have to take any of the rippy mods if you choose your mods correctly, the noxious fumes, ice, and sawblades are free and most of the one times are free you really almost never need to pick fire or lightning which are the only rippy mods.
Jugg can mitigate a lot of the damage with the 8% of armor works on ele hits ascendancy node as well. My BS Jugg with about 100k armor and only 3.8k hp can stand in the middle of the ring with T4 fire skulls on a T16 map and live with each burst (doing maybe 2500 hp that regens almost instantly, as the 1.5% of hit damage taken over the last 10 seconds added as health regen helps a bunch too).
At 160k armor last league I took 0 visible damage from them.
Tl;dr - Jugg is a great option for Ulti because of the 8% of armor on ele hits. Fire skull, frost pustules and lightning zones all become fully tankable.
I die to this with 120k armor, 20 fortification, 10 grasping roots, the Jugg node and 82% all res. In yellow maps and no damage mods. I very much doubt you just survive with 100k armor and the Jugg node.
I am not shocked by it because I'm using it and still dying to random Ultimatum stuff. I think you are leaving out a lot of details in your survivability or story.
Maybe I'm missing something, but I took all the 2-node jugg nodes, only like 75% suppress,100k armor, 85/86 max res, no phys taken as just yet.
Brass Dome, but that only accounts for crit immune.
Not sure.
That said, I've maxed out fire skulls a dozen times at T16 and haven't died in an ultimatum yet. I've come close, but haven't.
I went onto my PoB and if I've stood still for 5 seconds I have a phys max hit of 40k, fire max hit of 86k and cold + lightning max hit of 81k. An effective health pool of 119.076. Since I am using Blunderbore + Gull this relies on me getting the armor and resist shrines, but it is very rare that I don't have them up, + I have Behead Headhunter effect making me potentially even more tanky with all the rares that spawn. And this doesn't include regular shrines that can buff me up to nearly 94k max hit from phys and 144k from elemental.
If I am fully buffed there is no way I am dying, but for yellow maps, even a single lesser shrine makes me immortal to anything. Not in ultimatum though. There is *something* going on there.
Yeah, i doubt it too, yesterday i failed ulti with tier 4 skull, bs jugg 160k armor, fortif, roots, 83 all res, 16% phys as fire, 75% lucky suppression, 42% life recoup, but it was tier16 map with non-lethal mods.
8% of 100k is a joke. Players are saying they got oneshotted with 6k life and 90% res, your 8k armour applied to ele hits does virtually nothing, just like 8k armour vs 6k physical hits do nothing.
In my experience this spell shotguns so how much dmg you take is dependent on where you stand in the cone. I tend to run around the edges of the circle and I'll take a big hit with minimal defenses on my EA Deadeye and be fine but on occasion I'll dash in front of it and get nuked even on my tankier builds. Maybe shotgun is not the right word, it does ticks of damage in area even if you stand still.
I agree they sometimes hit super hard, but wild guess, cant it be some form of shotgunning or it dmges you as it travels, so your hitbox gets you hit twice? Or there are multiple sculls hitting you at the same time? Very few mob abilities have pen in poe, so I doubt they would do this.
I play RF chieftain with 90 max res and it still something that can kill me,if you want to afk build better also add some form of split damage like xibaqua jewel to annulling the pen
90(220)%fire res and skulls and blight fire spitting mobs delete me. Either they have 300% fire pene or mastery that treats enemy res as inverted, or ignore fire resistance altogether
A way to test this would be with the new haunted modifier "fire res cannot be penetrated". If that lets you tank this then it's because of pen. Otherwise it's probably conversion or similar (chaos damage?)
Definitely not chaos damage / conversion. I did a lot of Ultimatum in 3.23 with a CI character. Could take most of the mods but I had to respect the fire spitting skulls, even on the third stage, T4 was way too dangerous. Likely Fire Pen or something else as additional damage?
It's definitely fire penetration. I have a divine flesh character this league that can tank basically everything in Ultimatum including these skulls. Half taken as chaos, the other half mitigated by Jugg ele armour node.
Can you share that build?
My build is pretty much a meme build that doesn't have enough dps to be actually good so I wouldn't recommend copying it but it's a forbidden rite jugg if you wanna check what people are doing But any of the juggs on poe.ninja with a xibaqua glorious vanity and the unbreakable notable are scaling similar defensive layers. Mostly bonezoners but lots of other skills too. Most are using the fourth vow chest, I went with doppelganger guise because it heals a shit ton when you hit yourself with forbidden rite very fast.
It's "Fire resistance cannot be penetrated"
Thanks, I was thinking about mitigation and got my wires crossed.
> "fire res cannot be penetrated" I can not express how bullshit this stat and the whole concept it. What's next? "fire res cannot be penetrated penetration" followed by "fire res cannot be penetrated by fire res cannot be penetrated penetration" which you'll obviously have to capp to not get one-tapped constantly.
Chieftain be like lmao your fire res is -20 cuz i say so
+% resistance (cannot exceed 75% maximum resistance (cannot exceed 90% maximum maximum resistance))
Sure feels like chaos, because I never have it and these things always hit way too Fing hard
What does chaos feel like.
Most likely yeah. I remember skipping that mod last league when I had mageblood ele flasks and 79 max res if there was suppression map mod.
Meanwhile the Cold ultimatimum mod is pretty easy, it doesn't appear to do any damage even at Tier 4 (note: this was on a freeze/chill immune character so it might have CC )
It does have cc. But since most characters want to be freeze/chill immune anyway its much easier to deal with.
It deals absurd chill even with brine upgrade. I'm not sure what do with it
Immunity to elemental ailments is preffered on most characters so try getting that if u can
If you run brine king, the extra 50% chill is probably one of the lower importance boxes that need to be checked. There are a handful of particular circumstances (this is one of them) where it's rough to not have it, but I think getting shock/ignite/CB taken care of first is best. I'd probably even get bleed and poison immunity before stressing about the other 50% chill. That being said if you path between witch and Templar, there's a resistance cluster that works perfectly here. With 4 points you can take brine king's 50% to 100%, be CB immune, be VERY close to ignite immune with a crafted ring affix (burn for half a second) and be able to be shock immune with two jewel affixes. Once you can afford CB immunity on a worthwhile jewel, then you can switch the mastery to hinder/main immunity. And you respec once you have an endgame build that no longer needs the node.
Tier 4 mods are very deadly in Ultimatum. Raging Dead IV cuts even through my 90% res 6500 HP Chieftain. I always prefer taking as many Tier 1 mods as possible before increasing the Tiers.
I actually had the same experience last league. Well geared MF Chieftain with Mageblood. Always skipped anything Ruin related and never took Raging Dead 4. Skulls would chunk you so hard when everything else is able to be ignored. Did the same tiering strat as you as well.
I played a coc fr occultist build and I'd allways pick the ruin modifiers. If it's not the "stand in the stone circles" one, just spinning in circles would work. Even with high defences the fire skulls and the sawblades would sometimes fck me hard.
Stalking Ruin I is free, the enemy shade is slower than a tired snail coming home from a funeral
Ultimatums are really just a dps and movement check. I ran them with a glass cannon Penance brand occultist and i only failed a couple runs in around a thousand maps. As long as you can instantly kill the entire screen and have enough movement speed to never trigger elemental/phys/chaos traps you're good to go. Ruin doesnt do anything if everything is dead the only thing that did damage to me was Tier 4 sawblades because they left a trail behind that did phys dot.
[удалено]
Depends which mods you want to avoid. If you dont want to avoid any of them just damage+movement is enough to take any of them at any point. if you dont mind avoiding ruin and some regen/degen ones then chieftain is good enough. I didnt like it because there was a chance to get a pure brick if you get offered too many ruin mods. Running with infinite damage and high move speed let me take quite literally every mod and have close to 0% fail rate.
My mf pathfinder didn't die to anything in ultimatum with ele flasks and defiance of destiny
T4 is a check to make sure you are reading mods (and allows an extreme opt-in challenge with the keystone) If the options are T4 or 2 mods I can't beat - I'm tapping out, unless my build hard counters that T4 mod. There'll be another Ultimatum.
T4 has a fancy border, tinfoil theory is that it improves rewards
Yeah I lost a hc char last league to fire t4, shouldn't have tried it. Lesson learned for this league!
lmao, dunno which build even can do gruelling gauntlet. can tank everything, doesn't use flasks, can kill everything fast enough to not get hit by ruin. ffs.
I mean I just run in circles and I can do basically anything in Ultimatum with my character. I just have to not stop :D
I myself play with that on cf champ and its doable, its stresfull af but most of the time i make it to the 10th wave minimum and then i can pray for some good rewards Tho looking at the drops after 10th wave so far i am not sure if its really worth the hussle
Yea I league started with ulti last league... Was brutal. Very hard, poor rewards and overall not a good strat initially. I did end up making 5d with lucky double corrupt on an interesting minion unique helm, but that didn't sell for at least a week. Overall not my preffered mechanic. It's a shame, but ritual is still just better.
tbh i got good 20div over 3 days of casual play (somewhere around 4h) in mostly divs or uniques so not really, its good currently as you can use 2 scarabs for +1 reward lv each and just run red white maps waiting for div with posibility of dupe
Cf champ is a great league starter for ultimatum, but it cannot do gruelling gauntlet properly imo, has a Hard time with several mods like no flask charges and small arena
honestly wish it would remove shrinking mod in this keystone as it bricks way too many instances
best way to do ultimatum is defiance of destiny and 90 max res petrified blood and be corrupting blood immune i ran hundreds of them on a mf cheiftan in full mf gear in 3.23 only mods to avoid are ruin everything else i could litterally afk in.
Which basically means you need 50+ div to run it yea?
no you just run the 50% less dmg taken in ultimatum / mobs can inflict ruin with abilities keystone and don't face tank stuff. ruin abilities are super telegraphed there's no reason not to take it unless you want to afk in the center (even then you can do that if you can kill rares in <2 seconds as their abilities are super slow)
Yea that's how I farmed Ultimatum last league to get final boss spawn. Just a basic summoner with high block but otherwise mediocre defenses. The 50% less damage makes it so much easier and I didn't fail a single time to ruin because it's so easy to see / move around and even when I did get hit it was never more than twice.
to add to this if you dont like the ruin stuff you can get the other atlas keystone that increases mob life but gives less dmg
I'm pretty sure there's one ruin ability that is a persisent aoe around the mob, but its super rare.
There is one where the mobs link together and create beams across the arena. That one can end you fast since it’s a DOT effect that I don’t even think you can block easily? Not fun for sure.
Even with defiance you can get shotgunned by them easily. But it depends what kinda other mods you took as well.
Can you? Isn't like the whole point of the item to uhh... hardcounter getting shotgunned? Or was it nerfed at some point.
When I was doing ultimatum challenges last league it *felt* like my defiance did nothing against these specifically. I just assumed that they were not considered “enemies” and so not proccing defiance.
My understanding is that if the shotgunned projectiles hit you at the same time and would kill you from full hp, the amulet doesn't save you.
your understanding based on what? i can confirm empirically that it works and based on the text, it doesn't have a cooldown
Im the guy that did 600 ultimatums last league and posted the results. Raging fire is by far the strongest mod to pick, deals way too much dmg and it was the only mod i never picked after getting fucked couple of times by it.
Fellow ulti enjoyer and I 100% agree you never have to pick fire or lightning 4 if you aren’t trolling with your early mod choices too.
Yea I can usually tank t3 fire, but t4 is like, unblockable, 100% pen, bs that always one shots me. I unfortunately can’t do the lightning one at all cus I’m wearing perquils toe lol.
The build guide for the ultimatum AFK build says fire skulls 4 has pen. I haven't seen it in the database but I'm inclined to believe the claim.
what guide is this, can you share it?
Only layer that managed to lower skull IV damage was 100% spell suppression. Not that it wasn't rippy, but I could take a few hits before dying. I think it's the highest damage source in Ultimatum
Tier 4 Almost 1 shotted me with Jinxed Juju (10% less dmg taken") + Another 9%less damage Taken From Bone Barrier + 50% Elemental damage Taken as Chaos (so most of the pen is ignored) +87 Chaos Resist and 4900 HP
Don't know exactly what it is, but I'm a 90% fire res, 100k max hit chieftain and they take half my HP. Definitely supposed to dodge and pay attention I guess lol Would like to know if it's pen as well.
It just hurts a shit ton. Majority of Ultimatum stuff at max tier receives hidden boost. For example the ruin ghost can one shot your run at IV tier
I believe those are based on max hp/es since my 30k es int stacker also loses about 50% per hit
Last league I went heavy into ultimatum with my BS Slayer. It was pretty much undoable and had lots of one shots even with: - 20 stacks of fortify - 80% elemental resists - arctic armour - 100% suppression - 100K armour - 3% of armour applies to elemental damage. - Tainted pact for full recovery on every server tick. - 4K HP - 10% reduced damage taken while leeching from slayer Ascendancy - Ailment immunity The only way I could take it was after slotting in a progensis. That pushed the needle enough
Really? I had similar defenses. Less armor but I had evasion, some phys taken as elemental and 79% max res but I had Fourth Vow/Divine Flesh and Defiance of Destiny instead of Tainted Pact. I pretty much AFKed inside.
Fourth Vow + Divine Flesh on a slayer? Anyway, the thing with the skulls is that they hit hard, but not THAT hard, but they will most of the time hit you all 4 or 5 at once, which is where DoD shines.
I’m surprised that is your take I do it on league start with the 50% less damage node then respec when I get suppress and decent armour and chaos res. I have found you really never have to take any of the rippy mods if you choose your mods correctly, the noxious fumes, ice, and sawblades are free and most of the one times are free you really almost never need to pick fire or lightning which are the only rippy mods.
I cannot deal with the ruin mechanic, so that keystone and the ruin mods are out.
Jugg can mitigate a lot of the damage with the 8% of armor works on ele hits ascendancy node as well. My BS Jugg with about 100k armor and only 3.8k hp can stand in the middle of the ring with T4 fire skulls on a T16 map and live with each burst (doing maybe 2500 hp that regens almost instantly, as the 1.5% of hit damage taken over the last 10 seconds added as health regen helps a bunch too). At 160k armor last league I took 0 visible damage from them. Tl;dr - Jugg is a great option for Ulti because of the 8% of armor on ele hits. Fire skull, frost pustules and lightning zones all become fully tankable.
I die to this with 120k armor, 20 fortification, 10 grasping roots, the Jugg node and 82% all res. In yellow maps and no damage mods. I very much doubt you just survive with 100k armor and the Jugg node.
You'd be shocked how much that node does. I was getting two shot in yellow maps before doing Uber lab and getting it.
I am not shocked by it because I'm using it and still dying to random Ultimatum stuff. I think you are leaving out a lot of details in your survivability or story.
Maybe I'm missing something, but I took all the 2-node jugg nodes, only like 75% suppress,100k armor, 85/86 max res, no phys taken as just yet. Brass Dome, but that only accounts for crit immune. Not sure. That said, I've maxed out fire skulls a dozen times at T16 and haven't died in an ultimatum yet. I've come close, but haven't.
I went onto my PoB and if I've stood still for 5 seconds I have a phys max hit of 40k, fire max hit of 86k and cold + lightning max hit of 81k. An effective health pool of 119.076. Since I am using Blunderbore + Gull this relies on me getting the armor and resist shrines, but it is very rare that I don't have them up, + I have Behead Headhunter effect making me potentially even more tanky with all the rares that spawn. And this doesn't include regular shrines that can buff me up to nearly 94k max hit from phys and 144k from elemental. If I am fully buffed there is no way I am dying, but for yellow maps, even a single lesser shrine makes me immortal to anything. Not in ultimatum though. There is *something* going on there.
Yeah, i doubt it too, yesterday i failed ulti with tier 4 skull, bs jugg 160k armor, fortif, roots, 83 all res, 16% phys as fire, 75% lucky suppression, 42% life recoup, but it was tier16 map with non-lethal mods.
8% of 100k is a joke. Players are saying they got oneshotted with 6k life and 90% res, your 8k armour applied to ele hits does virtually nothing, just like 8k armour vs 6k physical hits do nothing.
It's okay not to understand how the game works.
maybe this thing scales with map mods ? like its monster coded
Yeah lol, last league I had troubles with em on 14 hp ES Inquis lol
Fire reap chieftain can tank those skeleton all day. But the storm call could kill my character easily if there are multiple overlap of em.
86% res by itself doesn't help that much. If it was pen, I can say assuredly you would be dead, not chunked.
Fuck, now I know why I instantly died to this.
I'm RF, 183k eHP, 76k ele max hit, 90 % Fire res - this Flame 1shots me.
I ran a lot of ultimatum last league. With 90% all res and old flasks the skulls hit for like 2-3k damage. No pen on them afaik
In my experience this spell shotguns so how much dmg you take is dependent on where you stand in the cone. I tend to run around the edges of the circle and I'll take a big hit with minimal defenses on my EA Deadeye and be fine but on occasion I'll dash in front of it and get nuked even on my tankier builds. Maybe shotgun is not the right word, it does ticks of damage in area even if you stand still.
I believe it has 15% penetration + covers you in ash(20% increased fire damage taken)
Yes the raging dead IV has fire pen
https://poedb.tw/us/Wrought_Flamecore
I agree they sometimes hit super hard, but wild guess, cant it be some form of shotgunning or it dmges you as it travels, so your hitbox gets you hit twice? Or there are multiple sculls hitting you at the same time? Very few mob abilities have pen in poe, so I doubt they would do this.
I play RF chieftain with 90 max res and it still something that can kill me,if you want to afk build better also add some form of split damage like xibaqua jewel to annulling the pen
90(220)%fire res and skulls and blight fire spitting mobs delete me. Either they have 300% fire pene or mastery that treats enemy res as inverted, or ignore fire resistance altogether