Pir, Imaginative Rascal + Karn, the Great Creator + Ugin's Nexus + The Chain Veil + Arcbound Ravager

Pir, Imaginative Rascal

Karn, the Great Creator

Ugin's Nexus

The Chain Veil

Arcbound Ravager

How it works

1. Activate Arcbound Ravager by sacrificing Ugin's Nexus.
2. Ugin's Nexus is exiled instead of being put into your graveyard, and causes you to take an extra turn after this one.
3. Resolve the Arcbound Ravager ability, putting two +1/+1 counters on it.
4. Activate The Chain Veil by paying 4 and tapping it, allowing you an additional activation of your planeswalkers' loyalty abilities this turn.
5. Activate Karn's first loyalty ability by putting two loyalty counters on it, causing any artifact to become an artifact creature until end of turn.
6. Activate Karn's second loyalty ability by removing two loyalty counters from it, revealing Ugin's Nexus from exile and putting it into your hand.
7. Move to your next turn.
8. Cast Ugin's Nexus by paying 5.
9. Repeat.