Fireball vs Orb - Demonweb Pits Data (no spoilers)

[Victim]

Yeah, at that level, high end metamagic rods are available, so characters can have both the Empower (or whatever) and the high level attack. Attacks that bypass energy resistance and have handy secondary effects are usually going to be worth the higher level slot. Something with just a higher damage cap (Polar Ray) isn't.

Besides, druids can use metamagic (and rods) too.