Olivia, Crimson Bride + Port Razer + Altar of Dementia

Olivia, Crimson Bride
Port Razer
Altar of Dementia

Requires
Port Razer is in your graveyard. All other permanents on the battlefield. Olivia does not have summoning sickness. An opponent is unable to block your creatures.
Steps
  1. Declare Olivia as an attacker, attacking an opponent unable to block your creatures
  2. Olivia triggers, returning Port Razer from your graveyard to the battlefield tapped and attacking that opponent
  3. Deal combat damage with Port Razer, triggering its ability, untapping all creatures you control and getting an additional combat phase after this one
  4. Activate Altar of Dementia by sacrificing Port Razer, causing target player to mill cards equal to Port Razer's power
  5. Repeat
Results
Infinite combat phases. Infinite ETB. Infinite LTB. Infinite death triggers. Infinite sacrifice triggers. Infinite mill. Infinite self-mill.