Ferocity

Enchant creature
Whenever enchanted creature blocks or becomes blocked, you may put a +1/+1 counter on it.
"Save yourself, my lord:
The ocean, overpeering of his list,
Eats not the flats with more impetuous haste
Than young Laertes, in a riotous head,
O'erbears your officers."
—Messenger. Act IV, Scene V