I thought about that, As the old Regen had Zombies and Skeletons. Then along came secrets and interactions and vanilla Necromancers, then I was like "Well that sucks" but then I thought why not make Liches? Lore-Wise, Liches are Necromancers that sought out pure immortality (no need to eat, drink, or sleep, etc..) and have mastered a wide range of spells. Since I needed a endgame creature that will make even the most strongest fortress scared, I decided to keep Skeletons. They can bleed to death still but it's very hard to do that, as hitting them turns their bones to dust (which leaves dusting because that is their blood)
Also technical isses? I know skeletons are or at least should be unraisable. So no need to worry about an evil biome or pesky necromancer bringing skeletons back to life. The rare and powerful lich caste needs more work atm. Right now it's basically a god, which is scary.
They are easy to remove as their entity lives in "entity_regen" past trogs and gremlins
Back to Lore
You mean DF lore? or Regeneration's Lore?
EDIT:
Ok was playing around with the new "Skull" and harder bone materials and reactions. And it is gltichy-er then I would have never thought. Not only does "make Skull Helm" take a skull and make a helm from it. But it forever grabs the helm making skull helms from the same helm afterwords until removed :/
And the harden bone reactions don't work at all, Which baffles me. It's too late for me to try and solve it. But it could be a typo somewhere, even if the errorlog swears nothing is wrong. Yay paper trails.