Idoneth Deepkin
The Idoneth Deepkin are fucking awesome. They are fish elves who ride giant fish into battle, what’s not to love?
Fluff
After Teclis, Tyrion, Malerion and Morathi made Slannesh start shitting out elf souls, Teclis took the first, those being the devout of Mathlann (a god who is dead) and taught these elves, the ‘Cythai’ about the old world. They had dark souls though, and after some spell shenanigans the elves fled into Atlantis the oceans and created several enclaves throughout the realms.
The elves, now the ‘Idoneth’ quickly found that their souls were weak and only one in a hundred survived. It took a while but eventually the Idoneth found that if you stab a bitch and put their soul into an elf, they wont die prematurely.
Nagash really hates these guys. So much so that he’s emptying an entire ocean just to make sure he can stamp them out because he’s the only guy who’s allowed to have dead souls.