Blue
Ravenous Bugblatter Beast of Traal
What I've come up with is a wand that serves mostly as an enhanced arcane focus. It can do random good things for the spells you cast. It might raise the effective level by 1. It might grand disadvantage to the save. Etc.
But on occasion (average 1 time in 6), it has to rid itself of the excess magic and probability it's built up, and does so by creating a wand of wonder effect.
I thought it was a cool way of getting the item in there while still making it something that's usually useful, and potent enough that the wizard will want to use it despite the occasional weirdness.
I'm not sure I prefer that, from either side of the DM screen. It makes it "mostly reliable to boost what I WANT to do", so when you don't get what you want to do, it feels like a real negative. So the "Wonder" part becomes a curse.