Medomai the Ageless + Preeminent Captain + Arcane Adaptation + Erratic Portal

Medomai the Ageless

Preeminent Captain

Arcane Adaptation

Erratic Portal

How it works

1. Declare Preeminent Captain as an attacker.
2. Preeminent Captain triggers, putting Medomai from your hand onto the battlefield tapped and attacking.
3. Deal combat damage with Medomai, causing you to take an extra turn after this one.
4. Activate Erratic Portal by paying 1 and tapping it, returning Medomai to your hand.
5. Pass the turn.
6. Repeat.