I, for one, don;t think this card needs an upkeep to balance it.
While my initial reaction was to think "OP" as well, I've yet to come up with any situation this card would be reliably OP in. On rare occasion you might have an "OMG! hax!!!" moment, but I don't think there'd be any decks that would prove super strong.
On to deck concepts. The immortal/creatureless decks people keep mentioning would NOT work well. since you'd be buffing your opponents creatures just as often as you'd cc them there's no real benefit to using this card there.
The best deck I can come up with for this would be an
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voodoo doll deck. If it cc's your voodoo doll it hurts the opponent, if it buffs the doll that hurts the opponent as well.