Basically say that anyone who looks at him makes a will save DC 70 each round or is permanently insane as the spell, and not even wish, miracle, etc. can cure them. Then give him Regeneration 40, an immunity to death effects, and spell reflection a la tarrasque. And he casts spellsmanifests as a lvl 20 psion. With that, you don't really need the rest of his stats. Although lotsa divine ranks couldn't hurt.