Eating a lesser nightmare corpse conveys a significant amount of poison resistance.
Lesser nightmares can grow up into nightmares, and then further into cauchemars.
By a route obscure and lonely,
Haunted by ill angels only,
Where an Eidolon, named NIGHT,
On a black throne reigns upright,
I have reached these lands but newly
From an ultimate dim Thule--
From a wild weird clime that lieth, sublime,
Out of SPACE -- Out of TIME.
[ Dream-Land, by Edgar Allen Poe ]