Ugin's Nexus + Aetheric Amplifier + Karn, the Great Creator + Atog

Ugin's Nexus

Aetheric Amplifier

Karn, the Great Creator

Atog

How it works

1. If Karn has exactly one loyalty counter on it, activate its first loyalty ability by putting a loyalty counter on it.
2. Activate Atog by sacrificing Ugin's Nexus. Ugin's Nexus will be exiled instead of being put into your graveyard due to its replacement effect, causing you to take an extra turn after this one.
3. Move to your next turn.
4. Activate Aetheric Amplifier by paying 4 and tapping it, doubling the number of counters on Karn.
5. Activate Karn's second loyalty ability by removing two loyalty counters from it, returning Ugin's Nexus from exile to your hand.
6. Cast Ugin's Nexus by paying 5.
7. Repeat from step 2.

This intricate setup locks down your opponents and chains together infinite turns by exploiting Ugin's Nexus and Karn, the Great Creator in a brilliant recursion loop. Karn's +1 ability animates the Nexus, allowing Atog to effortlessly sacrifice it; instead of hitting the graveyard, the Nexus exiles itself and grants you an extra turn. From there, Aetheric Amplifier steps in to effortlessly double Karn's loyalty counters so that Karn's −2 ability can reach into exile, fish Ugin's Nexus right back to your hand, and set the whole cycle up to cast and repeat all over again.