How about putting a 3-turn timer on it?
Or maybe 2-turns?
I think the problem with this is spark. Anything that will increase HP will be OP with Sparktal.
One thing to keep in mind is that this benefits both sides almost equally (except for mono airs).
I don't think dive is THAT OP. Unless both wyrms and pegasi are used, then CP is usually superior. With 6 CP in a deck and being incredibly cheap and usually granting more than +2|+0, it should be superior to a more expensive but more mass-buff card (unless you have more than 6 diving creatures, e.g. wyrms+pegasi)
Also, "Synchronized" is spelled incorrectly.