Miasmis The Fallen

+1: Put a 1/1 Green Black Wyrm with Wither on the battlefield.
0: Miasmis becomes a 3/3 Rogue with "This creature cannot be blocked by creatures with -1/-1 counters on them" until end of turn.
-5: Distribute X +1/+1 counters between creatures you control, where X is equal to the number of -1/-1 counters on the battlefield.