Goa\'uld Staff Cannon

Equip {3} Equipped creature gets +2/+2 and has trample. Equipped creature doesn’t untap during its controller’s untap step. At the beginning of your combat on your turn, you may pay {2}. If you do, untap equipped creature and it gains annihilator 1 until end of turn. Whenever equipped creature deals combat damage to a creature, destroy that creature.