Requires

Tawnos, Solemn Survivor must be on the battlefield. Retreat to Coralhelm must be on the battlefield. Caged Sun must be on the battlefield. Seat of the Synod must be in the graveyard. Tawnos does not have summoning sickness. "Blue" chosen with Caged Sun. You control at least two artifact tokens. Mana needed:

Steps

1. Activate Tawnos' second ability by paying , tapping it, sacrificing two artifact tokens and exiling Seat of the Synod from your graveyard, causing you to create a token of Seat of the Synod.
2. When the Seat of the Synod token enters the battlefield, Retreat to Coralhelm triggers, untapping Tawnos.
3. Activate the Seat of the Synod token by tapping it, adding .
4. Caged Sun triggers, adding .
5. Activate Tawnos' first ability by paying and tapping it, creating a copy of the Seat of the Synod token and causing you to mill two cards.
6. Repeat from step 2.

Results