So, I have a Bjornaer magus with Harnessed Magic, flying around as a giant eagle with miniaturized-boulders in his claws. As he flies over his enemies, he drops a boulder on them, at the same time concentrating to release the miniaturization-spell so that the enemy will be struck by the full-sized boulder. Now - what are the mechanics for this? I'm a bit at a loss, so I'm hoping the community will lend me its wisdom
I don't want to disallow it, it's fun (for him; less for the target).
What Aiming/Attack roll to use? I was thinking either Perception + Finesse or Dexterity + ... Brawl? A new "Rock Dropping" skill?
Should there be a penalty to the roll? He's trying to do three things at once here - flying, dropping the thing right on the target, and releasing the spell. It feels like this should incur a penalty somewhere, I'm not sure if it should be on the aiming/targetting roll (or how much penalty to give).
What's the Concentration EF for doing all of that?
How much damage? If he hits.
Inquiring minds want to know.