Shalai and Hallar, and Citizen V, Helmut Zemo

Prerequisites

• Shalai and Hallar on the battlefield
• Citizen V, Helmut Zemo on the battlefield

Steps

1. Give Shalai and Hallar lifelink, if needed
2. Gain life
3. Citizen V triggers, putting a +1/+1 counter on it
4. Shalai and Hallar triggers, dealing damage to an opponent and causing you to gain life
5. Repeat from step 3

Results

• Infinite +1/+1 counters on a creature
• Infinite damage
• Infinite lifegain
• Infinite lifegain triggers