This came up in our Second Darkness campaign today... yesterday. My Wizard is a Universalist, and he carries the Staff of Dark Flame found early in the AP. At level 12 I have 3 slots of Metamagic Mastery and wanted to use 2 of them to Empower a Fireball cast via the Staff. Legal? Not Legal?
The DM made a quick call and allowed it to work, but I wanted to run it by everyone here and see what the consensus is.
Arguments:
Since the spell is cast at your caster level instead of the staffs and because the metamagic slots are consumed, I can see some logic to allowing it to work.
But at the same time, since the spell is not powered by your personal spell slots, I can see logic to not allowing it as well.
I don't see much of a problem with allowing it, nor can I find a rule that would directly contradict it.