Requires

Prototype Portal must be on the battlefield. Ugin's Nexus must be in exile (exiled by Prototype Portal). Sarcatog must be on the battlefield. Mana needed: each turn

Steps

1. Activate Prototype Portal by paying and tapping it, creating a token copy of Ugin's Nexus.
2. Activate Sarcatog by sacrificing the Ugin's Nexus token.
3. The Ugin's Nexus token is exiled instead of being put into your graveyard, causing you to take an extra turn after this one.
4. Resolve the Sarcatog ability, giving it +1/+1 until end of turn.
5. Repeat each turn.

Results