Elbrus, the Binding Blade // Withengar Unbound, Walking Ballista, Agatha's Soul Cauldron, and Phyresis

Prerequisites

• Elbrus, the Binding Blade // Withengar Unbound on the battlefield
• Walking Ballista in exile
• Agatha's Soul Cauldron on the battlefield
• Phyresis on the battlefield
• Elbrus on the battlefield as Withengar Unbound
• Withengar Unbound does not have summoning sickness
• An opponent cannot block Withengar Unbound, or cannot prevent at least ten trample damage from Withengar Unbound
• Walking Ballista exiled by Agatha's Soul Cauldron

Steps

1. Deal combat damage to an opponent using Withengar Unbound, causing them to get at least ten poison counters
2. The opponent loses the game as a state-based action due to having ten or more poison counters
3. Withengar Unbound triggers, putting thirteen +1/+1 counters on it
4. Activate Withengar Unbound using Walking Ballista's second ability by removing a +1/+1 counter from it, giving an opponent a poison counter
5. Repeat step 4 until the opponent loses the game as a state-based action due to having ten or more poison counters
6. Repeat from step 3

Results

• Each opponent loses the game