So I am creating a dungeon, with the theme being mostly aberrations. The party is level 15, and heavily optimized.
Here's the group:
Radiant Servant of Pelor, uses DMM Persist (can do about 6 a day now),
Rogue/Master Thrower,
Sorcerer/Spellwarp Sniper,
Abjurant Champion gish.

I already have an Omnimental in the works, beholders, aboleths, and enough environmental hazards to keep them distracted. I need one more creature, and am open to ideas.

Thoughts?