Experiment Mayhem

Experiment Mayhem's power and toughness are
equal to the number of +1/+1 counters on it
plus 1.
Counters stay on Experiment mayhem as it
moves to any zone except a player's hand or
library.
When Experiment Mayhem dies, it deals damage
equal to the number of +1/+1 counters on it to
each other creature.