they were fantastic demons and devoted servants of the legion, who attacked quelthalas and wanted to destroy azeroth.
In quelthalas nowadays there are no more Fel crystals, they were all replaced by mana crystals. I think a lot of people want to play the evil faction. but blood elves are not evil. They are not evil demons and they are not cannibal zombies.
I hope they give us personalization that respects our lore and our aesthetics