Treebeard, Gracious Host + Scurry Oak + Prosperous Innkeeper

Prerequisites

• You have a way to gain life.

Steps

1. 1Gain life.
2. 2Treebeard's second ability triggers, putting that many +1/+1 counters on Scurry Oak.
3. 3Scurry Oak triggers, creating a 1/1 Squirrel creature token.
4. 4When the Squirrel enters the battlefield, Prosperous Innkeeper triggers, causing you to gain life.
5. 5Repeat from step 2.

Effects

• Infinite +1/+1 counters on a creature
• Infinite creature tokens
• Infinite ETB
• Infinite lifegain
• Infinite lifegain triggers