Walking Ballista, Unspeakable Symbol, and City on Fire

Prerequisites

• Walking Ballista on the battlefield
• Unspeakable Symbol on the battlefield
• City on Fire on the battlefield
• undefined

Steps

1. Give Walking Ballista lifelink, if needed
2. If Walking Ballista has less than two +1/+1 counters on it, activate Unspeakable Symbol by paying 3 life, putting a +1/+1 counter on Walking Ballista
3. Activate Walking Ballista's second ability by removing a +1/+1 counter from it, dealing 3 damage to an opponent or a permanent an opponent controls, and causing you to gain 3 life
4. Repeat from step 2

Results

• Infinite damage
• Infinite lifegain triggers