Infinite Reflection + Phyrexian Altar + Sepulchral Primordial

UB identity

Commander legal

The 3 combo pieces

What must be in place

You have a way to cause a nontoken creature to enter the battlefield under your control.

How to execute it

  1. Cause a nontoken creature to enter the battlefield under your control, which enters as a copy of Sepulchral Primordial due to Infinite Reflection.
  2. When the creature enters, it triggers. Holding priority, activate Phyrexian Altar by sacrificing the creature.
  3. Resolve the creature's trigger, putting a creature card from an opponent's graveyard onto the battlefield under your control as a copy of Sepulchral Primordial.
  4. Repeat from step 2.

What the combo produces