Destroy each creature that enters the battlefield under an opponent's controlDestroy all creatures opponents controlLock
How it works
Activate Goblin Sharpshooter by tapping it, dealing 1 damage to a creature an opponent controls.
The creature dealt damage dies as a state based action due to having 1 toughness and 1 damage dealt to it, triggering Goblin Sharpshooter, untapping Goblin Sharpshooter.
Repeat as desired.
You may also repeat this loop whenever a creature enters the battlefield under an opponent's control.