You could instead use the Trancer build for casting things yourself.
By level 15, a Wizard is an effective demigod. He can reshape the world, retire to his flowing time demiplane where a century there is a second in normal time, return to the normal world where he continues to reshape it, hide out in his demiplane awhile, and repeat.
Time stop alone can radically alter fights. Every CO caster of appropriate level uses it.
Remember, Epic means just that. Each character sheet is a book. Unless antimagic field is prevalent (and sometimes if it isn't), fights are initiative wars: Go first and win the fight. Casters can do this while non-casters typically can't, and if you're epic, why can't you cast?