Observe the food chain:
See, Illithid are on top.
Nobody eats our brains.
Once, the planes were ours.
The Gith slaves rebelled and won.
A minor setback.
Zombies munch brains too.
They are foul competition.
Flay necromancers!
Why do you fight back?
You are destined to serve us.
Or be served to us.