ToME: the Tales of Maj'Eyal

I have recently obtained the 'Poison Spit' from an escort on my skeleton rogue.

However when I try to use it, I get the error message 'You are too disconnected from nature to use Poison Spit'

What's this about? I suppose I wasted an escort point but I'd still like to understand what the limitations are.

Undead races can't use Wild Gift powers, which include Poison Spit.

Thanks. Must have missed it on the character creation screen.

Edit: Looks like it's not spelled out in the character creation screen. The wilder classes aren't available though.
Could use a clarification somewhere, or preferably disabling the escort rewards that won't ever work.

I think that is the only escort reward you can take that isn't usable.