Athreos, Shroud-Veiled + Ugin's Nexus + Karn, the Great Creator + Master Transmuter + Phyrexian Altar
How it works
- Activate Karn's first loyalty ability by putting a loyalty counter on it, causing Ugin's Nexus to become an artifact creature until end of turn.
- At the beginning of your end step, Athreos' second ability triggers, putting a coin counter on Ugin's Nexus.
- Activate Phyrexian Altar by sacrificing Ugin's Nexus, adding .
- Ugin's Nexus is exiled instead of being put into your graveyard, causing you to take an extra turn after this one.
- Athreos' third ability triggers, causing you to return Ugin's Nexus from exile to the battlefield.
- Activate Master Transmuter by paying , tapping it and returning Ugin's Nexus to your hand, choosing to not put an artifact onto the battlefield.
- Move to your extra turn.
- Cast Ugin's Nexus by paying 5.
- Repeat.
This intricate loop locks down extra turns by weaponizing the replacement effect of Ugin's Nexus, which normally prevents extra turns unless you circumvent it by exiling the artifact directly from the battlefield. Karn, the Great Creator plays a crucial foundational role here by turning that Nexus into an artifact creature with its +1 ability, making it a legal target for Athreos, Shroud-Veiled to tag with a coin counter during your end step and for Phyrexian Altar to sacrifice for mana. Once the Nexus is sent to the graveyard and exiled for its bonus turn, Athreos’s triggered ability immediately returns it from exile to the battlefield. Finally, Master Transmuter provides the alternative route to bounce the Nexus back to your hand if needed, allowing you to recast it and repeat the cycle indefinitely.