Tainted Observer, Mana Echoes, and Scurry Oak

Prerequisites

• Tainted Observer on the battlefield
• Mana Echoes on the battlefield
• Scurry Oak on the battlefield
• You have a way to cause a creature to enter the battlefield under your control
• Scurry Oak has at least one +1/+1 counter on it
• available

Steps

1. Cause a creature to enter the battlefield under your control
2. When the creature enters the battlefield, Tainted Observer and Mana Echoes triggers
3. Resolve the Mana Echoes trigger, adding for each creature that shares a creature type with the creature that entered the battlefield
4. Resolve the Tainted Observer trigger, causing you to pay to put a +1/+1 counter on Scurry Oak
5. Scurry Oak triggers, creating a 1/1 Squirrel creature token
6. Repeat from step 2

Results

• Infinite +1/+1 counters on Scurry Oak
• Infinite colorless mana
• Infinite creature tokens
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite proliferate
• Infinite sacrifice triggers