Living Death + Dualcaster Mage + Altar of Dementia

Living Death
Dualcaster Mage
Altar of Dementia

Requires
Altar of Dementia on the battlefield. Living Death and Dualcaster Mage in hand. 4bbrr available.
Steps
  1. Cast Living Death by paying 3bb
  2. Holding priority, cast Dualcaster Mage by paying 1rr
  3. Dualcaster Mage enters the battlefield, copying Living Death
  4. Holding priority, Activate Altar of Dementia by sacrificing Dualcaster Mage, causing target player to mill two cards
  5. Resolve the Living Death copy, exiling all creatures from graveyard, then sacrifices all creatures, then putting all cards exiled this way onto the battlefield
  6. Repeat from step 3
Results
Infinite ETB. Infinite LTB. Infinite mill. Infinite self-mill. Infinite sacrifice triggers.