Ummnn I'ma disagree here. I've done games with a divine template running around, and I recall the usual strategy of hell being throw in two legions, use pit fiends wishes to supress reality altering and have two archfiends finish things off but not to derail...
Setups are easy. Hell and Abyss come in for a final confrontation through selected archfiends and their followers. a confrontation of sexual prowess muahahahaha!
*random ideas are random*
Edit: a legion is basically the force of an entire layer of hell. Just for simple comparative purposes .. you ask us to be lvl 20 ish. Deities start at about lvl 40. *shrugs*