I would personally combo this with voodoo dolls I think.
A little less ATK bump, but +8 / +10 ATK isn't bad and it also yields an instant 8 / 10 damage.
So it ends up be 2
+ 3
for an 8|8 / 10|10 and 8 / 10 damage to opponent. Seems pretty good to me.
The massive dragon combo is definitely a show stopper though... 11
+ 3
for a 23|15
The largest output, of course, comes from flown titans... 5
+ 1
+ 3
for a 32|25 (with momentum too)...so I guess thats a good reason to not allow weapon targets.
Of course there are a LOT of mono synnergies. AM and maxwell's demon are the two that come to mind first.
With maxwells demon, you are guaranteed an auto kill combo for any creature that has an ATK above 0!
The limited duration is a little odd... I'm guessing its there for balance, but considering the punch it delivers when used with its most likely combo's I don't think it really does much for balancing. I think you may be better off just bumping cost by 1 point for unupped.