AP Pyro is gonna look like this, give or take a few points here and there depending on playstyle
https://classicdb.ch/?talent#oi0VfocquxxMzrZ0h
The specs arent that dependent for what you're asking, you basically just frost nove, flamestrike, and then wipe up with arcane explosion. You can do that almost equally with any mage spec since those skills aren't attached to anything necessary in the talent trees, just small benefits. So just look for spec stuff that would make your own life easier.

If you want to play around with fire/frost aoe, this spec has incredible off the charts aoe burst with nova, flamestrike, Cone of cold, blastwave and shatter ignite.
https://classicdb.ch/?talent#oZVg0df0uZMAG0obth