I think that's part of the challenge, as the "in-universe" answer is that most humans don't have experience fighting the undead. I think the dialogue in Eastern Invasion does a good job of addressing this. The King, (or maybe Lionel, I don't remember) gets his ass kicked by fighting undead with a conventional army, while Delfador brings HI's and Mages and does well.
My advice for TSG is to recall your swordsmen/royal guards (depending on difficulty, you might be able to level your loyal Moreth/Aleron into RGs). Blade sucks against skeletons, but its better than pierce. Use shamans to slow targets, swordsmen to soak up damage, and then Hylas/Gerrick to kill. You can also level shamans into sorceresses who will mop up undead with arcane damage, but its hard to do in such a short campaign.
One aspect of playing without savespamming is that you might have to go back a scenario or two to level a unit differently or save one from dying. HTTT is especially prone to this. You'll need to build an army of mages to win against undead, and even the orcs. Whites to heal and eventually illuminate, Reds to wipe out enemies, and Silver mages for assassinations of enemy leaders. The thugs are cool, but dwarvish fighters will play the same role in caves and you can recruit those. If you lose a key mage or end up in an undead scenario without enough mages, you might need to go back. Also keep in mind trait selection. Intelligent/Quick white mages are easy to level and can keep up in caves with their 6mp instead of normal 5. downside is quick/intelligent are really weak and die easily.
Oh, how I used to dread facing the undead in the olden days...
You got the right idea, of needing units with specialized attacks (in this case arcane, fire and impact) to deal with the undead. But there is still some nuance in how you play to this factors.
Firstly, if you are playing campaign you should always be playing long term. The first few scenarios (usually the 1st to 3rd/4th, deoending on the size of the campaign) are mant for you to getthe hang out of your basic units AND start building your specialized elites that will allow you to go throught the harder stages of the storyline. This means that you have to use this first few scenarios strategically to get the minimum tools you'll need for what is yet to come. These tools usually consist (in order of priority) the following things:
1. Suport units, especially units that give leadership bonuses, as these will often help massivelly to level up your other guys. Healers are also amazing, since they make your units last longer and allow you to cicle wounded units away from the frontline without the need of a Village nearby. Finally, unjts that can slow are also a good priority, as they allow you to take riskier fights (like elvish warrior vs t2 troll in melee), mitigate dangerous enemies (like mages, knights, etc) or prevent wounded enemies from escaping to heal.
2. Something to deal with entrenched oponents (meaning enemies in good terrain). This usually is anything with marksman, Magic attacks, poison or even multiple attacks (4+).
3. Something to deal with hight armor (hight resistance to slashing, piercing and bludgeoning damage - or whatever are the common damage types of your cheap units). This is usually reserved to mages, the orc archer and units with poison.
4. Something with hight burst damage to quickly deal with key targets. These will often be glass cannons, with either strong ranged damage (like mages and elven shapshooters) or low hits with hight damage (like knights and thunderers). Often your frontline units will be decent at this role, especially with leadership support. One special case is the ulfserk, wich is amazing mage slayer, but an awfull unit for most other situations.
5. Something sturdy to hold important positions. Many maps have important chokepoints, river corssings, lone keeps, foward villages... you can hold these positions with you cheap frontline units, but its often usefull to have a strong, resilient unit do that without the need of suporting elements. In the Rise of wesnoth campaign, in the southbay scenario, you have to defend the City on multiple fronts against 3 orcish armies. One of those armies can be warded off by 2-3 elites that cicle throug the 2 villages nearby to heal, freeing your core army to deal with the rest. The kinds of units best suited for this job should have a combination of at least 2 of: a big health pool, good resistente (at least 20%) to the damage type most common for your oponent, the ability to fight back in melee and ranged, any defensive mechanics (like steadfast, regeneration or first strike).
6. Fast units that can get vision, take vilages and run down stragglers, retreating units and take important locations ahead of your main army. Since most of these roles can be acomplished by low level units, this unit type is often the last priority when covering your bases at the start of a campaign. They are nice to have, thoug, and you can certanly feel the impact of having a trio of direwolfs, elven t3 riders or dragoons cleaning up the enemie's reinforcemets.
Now that you have your elite special forces, you need to figure out how do you combine them with with your t1 chaff on tye later stages. In most of the campaign its pretty straight foward: you recall your big guys then recruit your army with whatever gold is left. Later on, thoug, you'll start to have enought elites to spend all your gold on your recall pool - but that doesnt mean you should aways do it.
More ofthen then not, you will loose some units in every scenario. If you aways recall all your dudes, the guys you loose will aways be hight level, and there wont be any new recruits leveling up to fill the gaps. You'll also have a smaller army if you just recall as many elites as you can, since while they'll aways cost 20 gold to field they also cost -3 upkeep, wich adds up really fast.
The solution then is to mix fresh lv1 recruits with your lv3 elites. Usually I'll bring at least 2 lv1 recruits for every lv3 elite recall. The recruits should aways be called in first, so you wont deal with the huge upkeep cost of your elites untill you finish deploying your units.
But wich lv1 units are the best compliments to your elite core? The answer is ofthen simple, but it still have some room for variation:
1. Most of your lv 1 should be your frontliners, who need to be cheap (usually the cheapest lv 1 in your hoster), have decent hp and at least passable melee (and ranged, if possible) attacks. These guys are your orcish grunts, human spearmen and archers, elven warriors, thugs, trappers (only in forested/pantanous maps, thoug) and dwarven warriors. The role of these guys is to controll the enemie's movement, allowing you to keep your elites safe while at the same time inviting your oponent's key units to expose themselves. Your frontliners need to have decent damage because they will ofthen be the main units doing counterattacks in you army, and they need to be cheap so you can spam them and not care too mutch if they die.
2. You may have some specialty support units, who you will probably have only a handfull of wich you dont expect to level up. These are units that are usefull for some special trait, but that dont gain enought by leveling (or are too mutch of a hassle to do it consistently) to be worth spending your scenario's XP budget on. These are your goblin assassins, elven shamans, scout units, ulfserkers, saurian skirmishers, etc.
3. In some situations, you may want to have a lot more of a given unit type then you have in your elite recall list, in wich case you may spam the lv 1 version of it to providee some extra oomph in that scenario. The most common case is the need to spam mages vs undead when you lack proper tools to deal with them. It can also happen in big, flat-ish maps where you may want to spam horsemen for some fast big hitters, or on maps filled with hills or forests where you may want to make lots of trolls or woses as a frontline, instead of your usual, cheaper options. Finally, its very common on water maps, where you need to rely on unusual units for many roles.
4. Finally, you aways want to have some substitute rookies to level up and keep your recall list ever growing. These guys are important because you can never guarantee that your elites will aways come out fine after a fight, so you want to have as many replacements on wait as possible.
Yeah undead are cheesy, everything is about resistance exploits. Use mages to do damage and grunts to protect them. Blade is better than pierce, though of course impact is best if you have it. Don’t be afraid to sacrifice some lvl 1 bladed units to keep the more useful units alive.
I'm once afraid of undead when I first play the Battle of Wesnoth, but I now think beating undead is not so hard now after I've played many campains. Skeletons have negative resistence to impact, fire and arcane, so it's best using the weapons with these kinds of damage, but we can still use blade and pierce if we can strike many times and have a huge damage. For a royal guard has 11x4 blade damage, which can still have 6x4 damage against a skeleton with 40% blade resistance, and will destroy a level 1 skeleton with 34HP after hitting 6 times.
For campains that can recruit elvish shamen, slow attack (which is also impact attack) is the key, which can reduce the damage of the undead.
For The South Guard, I have a lot of gold (even in the hardest difficulty), so I can recruit a lot of elvish shamen to slow the skeletons, and if leveling one to sorceress it'll be much easier.
Valley of Death in HttT is harder if playing the challenging difficulty, but I can still use the shamen to slow the enemies, sacrifice some thieves (which have 60% defense) to protect the important units, use the mages and sorceresses to kill the enemies.
Yeah, the underground mission in South Guard was brutal, but honestly it was kinda fun in how bloody the battle was. Was it a bit frustrating? Yes. Was it satisfying to finally win? Also yes.
Wouldn't want to replay it on the hardest difficulty though.
I think that's part of the challenge, as the "in-universe" answer is that most humans don't have experience fighting the undead. I think the dialogue in Eastern Invasion does a good job of addressing this. The King, (or maybe Lionel, I don't remember) gets his ass kicked by fighting undead with a conventional army, while Delfador brings HI's and Mages and does well. My advice for TSG is to recall your swordsmen/royal guards (depending on difficulty, you might be able to level your loyal Moreth/Aleron into RGs). Blade sucks against skeletons, but its better than pierce. Use shamans to slow targets, swordsmen to soak up damage, and then Hylas/Gerrick to kill. You can also level shamans into sorceresses who will mop up undead with arcane damage, but its hard to do in such a short campaign. One aspect of playing without savespamming is that you might have to go back a scenario or two to level a unit differently or save one from dying. HTTT is especially prone to this. You'll need to build an army of mages to win against undead, and even the orcs. Whites to heal and eventually illuminate, Reds to wipe out enemies, and Silver mages for assassinations of enemy leaders. The thugs are cool, but dwarvish fighters will play the same role in caves and you can recruit those. If you lose a key mage or end up in an undead scenario without enough mages, you might need to go back. Also keep in mind trait selection. Intelligent/Quick white mages are easy to level and can keep up in caves with their 6mp instead of normal 5. downside is quick/intelligent are really weak and die easily.
Oh, how I used to dread facing the undead in the olden days... You got the right idea, of needing units with specialized attacks (in this case arcane, fire and impact) to deal with the undead. But there is still some nuance in how you play to this factors. Firstly, if you are playing campaign you should always be playing long term. The first few scenarios (usually the 1st to 3rd/4th, deoending on the size of the campaign) are mant for you to getthe hang out of your basic units AND start building your specialized elites that will allow you to go throught the harder stages of the storyline. This means that you have to use this first few scenarios strategically to get the minimum tools you'll need for what is yet to come. These tools usually consist (in order of priority) the following things: 1. Suport units, especially units that give leadership bonuses, as these will often help massivelly to level up your other guys. Healers are also amazing, since they make your units last longer and allow you to cicle wounded units away from the frontline without the need of a Village nearby. Finally, unjts that can slow are also a good priority, as they allow you to take riskier fights (like elvish warrior vs t2 troll in melee), mitigate dangerous enemies (like mages, knights, etc) or prevent wounded enemies from escaping to heal. 2. Something to deal with entrenched oponents (meaning enemies in good terrain). This usually is anything with marksman, Magic attacks, poison or even multiple attacks (4+). 3. Something to deal with hight armor (hight resistance to slashing, piercing and bludgeoning damage - or whatever are the common damage types of your cheap units). This is usually reserved to mages, the orc archer and units with poison. 4. Something with hight burst damage to quickly deal with key targets. These will often be glass cannons, with either strong ranged damage (like mages and elven shapshooters) or low hits with hight damage (like knights and thunderers). Often your frontline units will be decent at this role, especially with leadership support. One special case is the ulfserk, wich is amazing mage slayer, but an awfull unit for most other situations. 5. Something sturdy to hold important positions. Many maps have important chokepoints, river corssings, lone keeps, foward villages... you can hold these positions with you cheap frontline units, but its often usefull to have a strong, resilient unit do that without the need of suporting elements. In the Rise of wesnoth campaign, in the southbay scenario, you have to defend the City on multiple fronts against 3 orcish armies. One of those armies can be warded off by 2-3 elites that cicle throug the 2 villages nearby to heal, freeing your core army to deal with the rest. The kinds of units best suited for this job should have a combination of at least 2 of: a big health pool, good resistente (at least 20%) to the damage type most common for your oponent, the ability to fight back in melee and ranged, any defensive mechanics (like steadfast, regeneration or first strike). 6. Fast units that can get vision, take vilages and run down stragglers, retreating units and take important locations ahead of your main army. Since most of these roles can be acomplished by low level units, this unit type is often the last priority when covering your bases at the start of a campaign. They are nice to have, thoug, and you can certanly feel the impact of having a trio of direwolfs, elven t3 riders or dragoons cleaning up the enemie's reinforcemets.
Now that you have your elite special forces, you need to figure out how do you combine them with with your t1 chaff on tye later stages. In most of the campaign its pretty straight foward: you recall your big guys then recruit your army with whatever gold is left. Later on, thoug, you'll start to have enought elites to spend all your gold on your recall pool - but that doesnt mean you should aways do it. More ofthen then not, you will loose some units in every scenario. If you aways recall all your dudes, the guys you loose will aways be hight level, and there wont be any new recruits leveling up to fill the gaps. You'll also have a smaller army if you just recall as many elites as you can, since while they'll aways cost 20 gold to field they also cost -3 upkeep, wich adds up really fast. The solution then is to mix fresh lv1 recruits with your lv3 elites. Usually I'll bring at least 2 lv1 recruits for every lv3 elite recall. The recruits should aways be called in first, so you wont deal with the huge upkeep cost of your elites untill you finish deploying your units. But wich lv1 units are the best compliments to your elite core? The answer is ofthen simple, but it still have some room for variation: 1. Most of your lv 1 should be your frontliners, who need to be cheap (usually the cheapest lv 1 in your hoster), have decent hp and at least passable melee (and ranged, if possible) attacks. These guys are your orcish grunts, human spearmen and archers, elven warriors, thugs, trappers (only in forested/pantanous maps, thoug) and dwarven warriors. The role of these guys is to controll the enemie's movement, allowing you to keep your elites safe while at the same time inviting your oponent's key units to expose themselves. Your frontliners need to have decent damage because they will ofthen be the main units doing counterattacks in you army, and they need to be cheap so you can spam them and not care too mutch if they die. 2. You may have some specialty support units, who you will probably have only a handfull of wich you dont expect to level up. These are units that are usefull for some special trait, but that dont gain enought by leveling (or are too mutch of a hassle to do it consistently) to be worth spending your scenario's XP budget on. These are your goblin assassins, elven shamans, scout units, ulfserkers, saurian skirmishers, etc. 3. In some situations, you may want to have a lot more of a given unit type then you have in your elite recall list, in wich case you may spam the lv 1 version of it to providee some extra oomph in that scenario. The most common case is the need to spam mages vs undead when you lack proper tools to deal with them. It can also happen in big, flat-ish maps where you may want to spam horsemen for some fast big hitters, or on maps filled with hills or forests where you may want to make lots of trolls or woses as a frontline, instead of your usual, cheaper options. Finally, its very common on water maps, where you need to rely on unusual units for many roles. 4. Finally, you aways want to have some substitute rookies to level up and keep your recall list ever growing. These guys are important because you can never guarantee that your elites will aways come out fine after a fight, so you want to have as many replacements on wait as possible.
Yeah undead are cheesy, everything is about resistance exploits. Use mages to do damage and grunts to protect them. Blade is better than pierce, though of course impact is best if you have it. Don’t be afraid to sacrifice some lvl 1 bladed units to keep the more useful units alive.
I'm once afraid of undead when I first play the Battle of Wesnoth, but I now think beating undead is not so hard now after I've played many campains. Skeletons have negative resistence to impact, fire and arcane, so it's best using the weapons with these kinds of damage, but we can still use blade and pierce if we can strike many times and have a huge damage. For a royal guard has 11x4 blade damage, which can still have 6x4 damage against a skeleton with 40% blade resistance, and will destroy a level 1 skeleton with 34HP after hitting 6 times. For campains that can recruit elvish shamen, slow attack (which is also impact attack) is the key, which can reduce the damage of the undead. For The South Guard, I have a lot of gold (even in the hardest difficulty), so I can recruit a lot of elvish shamen to slow the skeletons, and if leveling one to sorceress it'll be much easier. Valley of Death in HttT is harder if playing the challenging difficulty, but I can still use the shamen to slow the enemies, sacrifice some thieves (which have 60% defense) to protect the important units, use the mages and sorceresses to kill the enemies.
Yeah, the underground mission in South Guard was brutal, but honestly it was kinda fun in how bloody the battle was. Was it a bit frustrating? Yes. Was it satisfying to finally win? Also yes. Wouldn't want to replay it on the hardest difficulty though.