Here are two more possible curbs for magic item abuse in my DF game.
This was suggested by one of my players:
Idea 8: One person only. By default, you can put a buff spell on only one target. It could be you or someone else, but only one at a time. You can cancel early, as usual (1 FP cost) if you want to switch targets, but otherwise you have to wait.
Notes: We'd need a d60 to really know where in the ongoing spell you were when a fight starts. Oddly different from how spells work now, but it seems pretty balanced against the other choices.
Idea 9: Item spells on other people count as spells "on." Any spell used on a target other than the magic item's owner counts as a spell on for all purposes, including casting your own spells or using another magic item. On yourself, it doesn't count towards the total.
Notes: This would undo something we've done for a while, which is say items cast by an item accumulate penalties to that item, only. This makes items without the Power enchantment dramatically less valuable.
And no, we still haven't decided. I'm sure we'll decide right before game starts on Sunday.