Gogo, Master of Mimicry, High Tide, Retreat to Coralhelm, Doppelgang, and Swarm Intelligence

Prerequisites

• Gogo, Master of Mimicry on the battlefield
• High Tide in hand
• Retreat to Coralhelm on the battlefield
• Doppelgang in hand
• Swarm Intelligence on the battlefield
• available

Steps

1. Cast High Tide by paying
2. Cast Doppelgang by paying its mana cost, targeting an Island you control
3. Swarm Intelligence triggers
4. Holding priority, activate Gogo by paying and tapping it, copying the Swarm Intelligence ability
5. Resolve the copy of Swarm Intelligence's ability, copying the Doppelgang spell, targeting an Island you control that enters the battlefield untapped
6. Resolve the copy of Doppelgang, creating a token copy of the targeted Island
7. When the Island token enters, Retreat to Coralhelm triggers, untapping Gogo
8. Activate the Island token by tapping it, adding
9. High Tide triggers, adding
10. Repeat from step 4

Results

• Infinite magecraft triggers
• Infinite landfall triggers
• Infinite tapped Island tokens