Ultimecia, Time Sorceress // Ultimecia, Omnipotent + Tetzin, Gnome Champion // The Golden-Gear Colossus + Memnarch + Thassa, Deep-Dwelling

Ultimecia, Time Sorceress // Ultimecia, Omnipotent

Tetzin, Gnome Champion // The Golden-Gear Colossus

Memnarch

Thassa, Deep-Dwelling

How it works

1. Activate Memnarch by paying 1, causing Ultimecia, Time Sorceress to become an artifact.
2. Declare The Golden-Gear Colossus as an attacker. It triggers, creating two 1/1 Gnome artifact creature tokens and transforming Ultimecia, Time Sorceress into Ultimecia, Omnipotent.
3. Ultimecia, Omnipotent triggers, causing you to take an extra turn after this one.
4. At the beginning of your end step, Thassa triggers, blinking Ultimecia, Omnipotent. It'll enter the battlefield as Ultimecia, Time Sorceress.
5. When Ultimecia, Time Sorceress enters, it triggers, causing you to surveil 2.
6. Repeat each turn.

This intricate loop achieves infinite turns by continuously cycling Ultimecia, Time Sorceress into her transformed state as Ultimecia, Omnipotent for her extra-turn trigger. Memnarch is crucial here as a permanent-type shifter, allowing you to treat Ultimecia as an artifact so she can be seamlessly manipulated by the rest of your engine. Tetzin, Gnome Champion, whose back face is The Golden-Gear Colossus, provides the ongoing transformation trigger when it attacks to flip Ultimecia back and forth while spitting out Gnome tokens. Finally, Thassa, Deep-Dwelling resets Ultimecia at the end step by blinking her back to her front face, ready to surveil and repeat the entire time-bending sequence on your next extra turn.