While not being raw I go with 10th level "rain of colorless fire", I translated the 3e version to create a low power version of it and used it in my greyhawk campaign. It was enough to turn 200 attacking orcs into an amorphous mass of burned swamp.
It is basically Armageddon light in its full power version, and wiped out two nations in official greyhawk lore.
Downside of it : it requires a very powerful artifact and is a ritual which potentially can kill those powering it, but it is fun anyway. (In the session I allowed the party to cast the low power edition of it, the party mage botched an arcana check, and one of the PCs who helped empowering it botched a save and instantly met his god)
It is basically Armageddon light in its full power version, and wiped out two nations in official greyhawk lore.
Downside of it : it requires a very powerful artifact and is a ritual which potentially can kill those powering it, but it is fun anyway. (In the session I allowed the party to cast the low power edition of it, the party mage botched an arcana check, and one of the PCs who helped empowering it botched a save and instantly met his god)