To be clear, this "kaboom mage" probably hasn't cast five Fireball spells in his life. Lightning Bolt? Fewer. Most of the time he doesn't even have those spells prepared.
His favorite spell is Grease, followed closely by Ray of Enfeeblement. Resilient Sphere is a great, non-lethal way of dealing with an adversary, and Stinking Cloud can disable without killing.
His big, go-to damage spell? Scorching Ray.
He's big on non-lethal spells, and I tried to get Non-Lethal Substitution for him early on, but it isn't in any of the books we've approved for the campaign.
The first time the party set out with him they were surprised that he'd prepared Unseen Servant, to set up his tent and prepare a meal, instead of some combat spell.
He had that and Grease prepared. Didn't even know Magic Missile or Shield.
He was a minor court dandy, literally dragged out of the crowd by the King so he wouldn't have to deal with the PCs directly.
He's spent his spare time finding odd objects to Shrink Item on, so he can have them handy. A 12 foot ladder, a long slab of iron that can act as a bridge. I think he has a door in there someplace, along with a campfire, a few party meals, all hot and ready, a ship's deck grating (5x5), a few empty chests, and some pretty-pretties so he has nice gifts available for when we visit someone important. Oh, and a few bottles of decent wine.
We play that an object subjected to Shrink Item can be kept in that state beyond the normal duration if you store it in something too small to allow expansion. There isn't a hard rule on it anyplace. The closest is the Enlarge Person spell, that says if there isn't room for the person to grow, they grow to the limits of the available space, unless they can break through the confinement with an Strength check. Since objects don't have a Strength score...
So he's far more of a utility mage, and a bit of a "Mr Pockets", than a kaboom type.
