Royal Assassin, Orb of Dreams, and Thornbite Staff

Prerequisites

• Royal Assassin on the battlefield
• Orb of Dreams on the battlefield
• Thornbite Staff on the battlefield
• Royal Assassin does not have summoning sickness
• Thornbite Staff attached to Royal Assassin

Steps

1. Whenever a creature enters the battlefield under an opponent's control, it enters tapped due to Orb of Dreams
2. Holding priority, activate Royal Assassin by tapping it, destroying the creature
3. The creature dies, triggering Royal Assassin, untapping Royal Assassin
4. Repeat

Results

• Destroy all creatures that enter the battlefield under an opponent's control