Infinite combat damageInfinite combat phasesInfinite creature tokens with hasteInfinite damageInfinite creature ETBInfinite mana creatures you control can produceInfinite untap of creatures you control
How it works
At the beginning of combat, Helm of the Host triggers, creating a token copy of Port Razer with haste.
Declare the Port Razer token as an attacker.
When the Port Razer token deals combat damage, it triggers, causing you to untap all creatures you control and get another combat phase after this one.