Whenever equipped creature attacks, put a +1/+1 counter on it.
Whenever equipped creature deals combat damage, roll a d12. If the result is greater than the damage dealt or the result is 12, double the number of +1/+1 counters on that creature.
Equip 2 (2: Attach to target creature you control. Equip only as a sorcery.)

NOTE: Stock image, not actual card.