Requires

Archelos, Lagoon Mystic must be on the battlefield. Zimone, Quandrix Prodigy must be on the battlefield. Retreat to Coralhelm must be on the battlefield. Rakdos Carnarium must be in hand. Zimone does not have summoning sickness. Archelos is untapped. Mana needed:

Steps

1. Activate Zimone's first ability by paying and tapping it, putting Rakdos Carnarium from your hand onto the battlefield untapped due to Archelos.
2. Rakdos Carnarium enters the battlefield, triggering itself and Retreat to Coralhelm.
3. Activate Rakdos Carnarium by tapping it, adding .
4. Resolve the Rakdos Carnarium trigger from step 2, returning itself from the battlefield to your hand.
5. Resolve the Retreat to Coralhelm trigger, untapping Zimone.
6. Repeat.

Results