Yooo, let's go Mystic Theurge! Maybe gestalt to hit those prerequisites faster and get a *third* spellcasting class in there?

The DM who permits theurge PrCs alongside gestalt rules deserves everything they're going to have to do to challenge such OP. It's me. I did it. I ended up building BBEGs whose myriad defenses needed to be stripped one at a time before they could be rocket tagged. Recalibrated after that campaign.

Lol, and die to a stray arrow to the knee with my abysmal Con.