Animated Rolling Snowball

Animated Rolling Snowball enters the battlefield with a +1/+1 counter on it.
Whenever Animated Rolling Snowball attacks, flip a coin for each +1/+1 counter on it. Put a number of +1/+1 counters on it equal to the number of flips you won.
Whenever Animated Rolling Snowball is dealt damage, roll a six-sided die. If you roll a 1, sacrifice it.