Activate Isochron Scepter by paying {2} and tapping it, casting a copy of Moonmist without paying its mana cost.
Resolve Moonmist, transforming Ultimecia, Time Sorceress into Ultimecia, Omnipotent.
Ultimecia, Omnipotent triggers, causing you to take an extra turn after this one.
At the beginning of your end step, Thassa triggers, blinking Ultimecia, Omnipotent and causing it to re-enter the battlefield as Ultimecia, Time Sorceress.
Whenever Ultimecia, Time Sorceress enters the battlefield, it triggers, causing you to surveil 2.
Repeat each turn.

Infinite turns

Ultimecia, Time Sorceress // Ultimecia, Omnipotent

Moonmist

Isochron Scepter

Thassa, Deep-Dwelling

At the beginning of your upkeep, Panoptic Mirror triggers, casting a copy of Moonmist without paying its mana cost.
Resolve Moonmist, transforming Ultimecia, Time Sorceress into Ultimecia, Omnipotent.
Ultimecia, Omnipotent triggers, causing you to take an extra turn after this one.
Deal combat damage to an opponent using Brago, triggering Brago, blinking Ultimecia, Omnipotent and causing it to re-enter the battlefield as Ultimecia, Time Sorceress.
Whenever Ultimecia, Time Sorceress enters the battlefield, it triggers, causing you to surveil 2.
Repeat each turn.

Combos with "Moonmist"