Insane Defiance on Nyarlathotep. It is necessary. Full stop.
Then have him use it to fuck up things with Mind-Affecting abilities. If you want something really funny, take a look at the Fear Handbook, and grab a 'friend' for him that pierces Fear Immunity (Dread Witch, most likely. After all, he would have a cult, wouldn't he?)
If Ghaele Eladrin are that outsider that gets infinite Bardic Music usages, may I suggest Doomspeak as one of the feats? Tasty -10 penalty to an enemy is tasty. Other than that, grab Lyric Spell and Metamagic Song. Infinite spells are infinite.
Nitocris needs Solicit Psycrystal (Feat), Psycrystal Affinity (Feat), Control Body, and Schism.
A Physical full-round action, a purely mental full round action, and 2 purely mental standard actions are nice and Eldritch-monstrosity like. Expanded Knowledge (Consumptive Field) might be nice, if you allowed StP Erudites into your game.