Treebeard, Gracious Host, Scurry Oak, and Distinguished Conjurer

Prerequisites

• Treebeard, Gracious Host on the battlefield
• Scurry Oak on the battlefield
• Distinguished Conjurer on the battlefield
• You have a way to gain life

Steps

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

Results

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