Agatha's Soul Cauldron, Triskelion, and Sephiroth, Planet's Heir

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• Triskelion in exile
• Sephiroth, Planet's Heir on the battlefield

Steps

1. If needed, give Sephiroth deathtouch
2. Activate Sephiroth using Triskelion's ability by removing a +1/+1 counter from it, dealing 1 damage to a creature an opponent controls and destroying it due to Sephiroth's deathtouch
3. When the creature dies, Sephiroth triggers, putting a +1/+1 counter on it
4. Repeat from step 2

Results

• Lock
• Destroy all creatures opponents control
• Destroy each creature that enters the battlefield under an opponent's control