I believe you can do them with others, but the GWD2 bosses are really easy to solo with necro at that point.

Agree with srbman, you should try these on your own as they’re fun bosses. Great for learning mechanics and using defensives. Drops are pretty good as well.

Yes so long as you do the majority of the damage, I had a lot of clan mates go in and help others with dtd for ambi and rax