Decaying Series

I have two issues with this card. One, I think that it is grossly underpowered. You have taken Unstable Mutation, which costs 1 mana, made it worse, then added a second ability to it that would normally cost 3 mana, except you have to wait to get the ability and will typically lose your creature in the process (although you could also play this on an opponent's creature, which occured to me only after I began my criticism.) Two, this card is, as you noted, very busy.

Realizing how you probably intended this to work, I still can't approve. You've taken a fairly simple concept -- destroying two of your opponent's creatures -- and made it very complicated. First you pump one of the creatures, then it slowly dies, and when it finally dies, only then does the other creature die (except it actually gets removed from the game, and only if it's not black.) In reality, I'm not really seeing a combination of Unstable Mutation and Verdant Force -- the fact that the -1/-1 counters (another concern) acculate every turn is trivial. I'm seeing a combination of Unstable Mutation and Dying Wail. That leaves me with the question: Why should there be a card that combines Unstable Mutation and Dying Wail? It would be better to combine one of those cards with something that complements it in an unusual way. For example, Erg Raiders + Dying Wail. Force them to put the creature into hazardous situations, but punish them for doing so. Or Unstable Mutation + Spike Drone -- give the creature some method of throwing the counters around (notwithstanding that -1/-1 counters are no longer supported.)