Duke Ulder Ravengard, and Port Razer

Prerequisites

• Duke Ulder Ravengard on the battlefield
• Port Razer on the battlefield
• Opponents are unable to block your creatures

Steps

1. At the beginning of your combat phase, Duke triggers, giving Port Razer haste and myriad until end of turn
2. Declare Port Razer as an attacker
3. Port Razer's myriad ability triggers, creating a token copy of Port Razer attacking each other opponent
4. Each Port Razer deals combat damage, triggering themselves, untapping each creature you control and causing you to get an additional combat phase after this one for each trigger
5. At end of combat, the token Port Razers' myriad abilities trigger, exiling them
6. Repeat once for each opponent

Results

• Near-infinite combat damage
• Near-infinite combat phases
• Near-infinite ETB
• Near-infinite LTB
• Near-infinite untap of creatures