Cool that don't agree queegon, but why? You should see my 40k shard cost deck. Ive gotten potted powerhouse up 8 points on turn six. That was just that turn. Ive brought out 20/20s multiple times.
Double mint. Does this already, but it gets health as well. If it makes it 2 turns untouched, you better play a deadly (or spell, if you've got any left after i play banana repeat and black eye) or it will eat your heavy hitters whole and heal+ back the next turn. At least mag is only damage...
That being said, i think it should be a condition, not just having it in your hand, but something like "damage doubles every turn you don't play a trick" or "damage doubles every zombie killed", etc.