I've never really found a good use for him. His range isn't very good (2-4) and his damage isn't very good either. I suppose if you are making a KF/UD split deck he might be a little better because of Ally: UD. In a KF/UD deck you might have some limited success with cloaking melee beaters and sneaking them in close. In FF KF, I have never found a good use for him. I don't think he was designed to be played. I think he was designed to be a reward.
Only plus with that ability (Ally: UD) in a FF group comes in the form of the Naria. What about Magic Acolyte and Magic Blast? So far, I've honestly just used him here and there as an AP boost on UD and KF/UD champions.
He is decent in a KF/UD stealth build. Equip him with Covenant and give him Stealth and Magic Acolyte, and he can be useful. Here is something close to what I had at one point. https://poxbase.com/deck/CtiClCj0cxCpBcx2C6dclWcxzc1bs5zsyS4@sDSLr3nr2Yr3fe1+e2FeNe2we1x
