Meandering Mudhorn

Whenever a creature enters the battlefield under
an opponent's control you may put a +1/+1
counter on that creature. If you do, put two
+1/+1 counters on Meandering Mudhorn.
Meandering Mudhorn cannot be blocked by creatures with +1/+1 counters on them.
"Don't worry about it. Those beasts are completely harmless."
—Random Soldier, last words