Walking Ballista, Unspeakable Symbol, Quest for Pure Flame, and The Rollercrusher Ride

Prerequisites

• Walking Ballista on the battlefield
• Unspeakable Symbol on the battlefield
• Quest for Pure Flame on the battlefield
• The Rollercrusher Ride on the battlefield
• Quest for Pure Flame has at least four quest counters on it
• There are four or more card types among cards in your graveyard
• You have a way to give Walking Ballista lifelink
• Walking Ballista has at least two +1/+1 counters on it, or your life total is at least 4

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 4 damage to an opponent or a permanent an opponent controls, and causing you to gain 4 life
4. Repeat from step 2

Results

• Infinite damage
• Infinite lifegain triggers
• Infinite lifegain
• Infinite +1/+1 counters