The character:

An illithid/illithid savant 5 eats the brain of 20th level archivist for spell casting as a 20th level archivist and the brain of protean for 'alter form'. It has 7 feats (5 from 13 HD, plus 2 from illithid savant).

1. ??
3. Twin Spell
6. Easy[Twin]
9. Martial Study[some L1 Iron Heart]
12. Martial Study[Iron Heart Surge]
IS2: ??
IS4: ??

Every day it casts foresight. It acquire Arcane Fusion by creating a divine scroll of Arcane Fusion with the (paid) contribution of Arcane Fusion from Sorcerer. It acquires Celerity in the same manner.

Upon learning of impending doom from foresight, it immediately casts Easy Twin Arcane Fusion[Celerity] from a 7th level slot as full-round action which grants 2 standard actions.
The first standard action casts Favor of the Martyr for immunity to the drawback of celerity.
The other standard action casts Easy Twin Arcane Fusion[Celerity] as a standard action which grants 2 standard actions.
The first standard action is a wish to transport to the thing as a standard action.
The other standard action casts Easy Twin Arcane Fusion[Celerity] as a standard action which grants 2 standard actions.
As a free action, the Illithid savant mimics the thing's form, acquiring it's impending doom ability,
The first standard action then uses the acquired ability on the creature.
The other standard action is Iron Heart Surge to end the condition currently causing impending doom on itself.
As a free action, use alter form to acquire a Colossus Antimagic Field (which is an Ex ability). As per the rules compendium, all incorporeal creatures (not just undead) disappear yet have a local time proceed within an antimagic field.
Wait 5 rounds, proceed with life.

The desired effect: Creature has no actions remaining, Doom ability ends on us, Creature is hit with it's own doom ability.