Roon of the Hidden Realm + Eternal Witness + Temporal Manipulation

Roon of the Hidden Realm

Eternal Witness

Temporal Manipulation

How it works

1. Cast Temporal Manipulation by paying 3, causing you to take an extra turn after this one.
2. Activate Roon by paying 2 and tapping it, exiling Eternal Witness until the beginning of your end step.
3. At the beginning of your end step, Roon triggers, returning Eternal Witness from exile to the battlefield.
4. Eternal Witness enters the battlefield, putting Temporal Manipulation into your hand from your graveyard.
5. Repeat each turn.