Tainted Observer, Mana Echoes, and Invisible Woman, Sue Storm

Prerequisites

• Tainted Observer on the battlefield
• Mana Echoes on the battlefield
• Invisible Woman, Sue Storm on the battlefield
• at most 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 the other Hero
5. Invisible Woman triggers, creating a creature token
6. Repeat from step 2

Results

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