Druid's Call, Cathars' Crusade, Walking Ballista, and Doubling Season

Prerequisites

• Druid's Call on the battlefield
• Cathars' Crusade on the battlefield
• Walking Ballista on the battlefield
• Doubling Season on the battlefield
• Druid's Call attached to Walking Ballista
• Walking Ballista has at least three +1/+1 counters

Steps

1. Activate Walking Ballista's first ability by removing a +1/+1 counter from it, dealing 1 damage to itself
2. Druid's Call triggers, creating two 1/1 Squirrel creature tokens
3. The Squirrels enters the battlefield, triggering Cathars' Crusade twice, putting four +1/+1 counters on each creature you control
4. Repeat
5. Once you have infinite +1/+1 counters on Walking Ballista, you may remove them to deal infinite damage to any target(s)

Results

• Infinite +1/+1 counters
• Infinite creature tokens
• Infinite damage
• Infinite ETB