Heal Cannon

Flash
Equip {2}
Equipped creature has "{t}: Put X number of time counters on this creature. Prevent the next X amount of damage that would be dealt to any target this turn. If this creature has any time counters on it, it cannot untap, you cannot unequip equipment from it, and you cannot use this ability."
At the beginning of your upkeep, remove a time counter from equipped creature