Cauldron of Souls, Dross Scorpion, Phyrexian Altar, and Encroaching Mycosynth

Prerequisites

• Cauldron of Souls on the battlefield
• Dross Scorpion on the battlefield
• Phyrexian Altar on the battlefield
• Encroaching Mycosynth on the battlefield
• An opponent was dealt damage this turn
• The creature with bloodthirst does not have a -1/-1 counter on it

Steps

1. Activate Cauldron of Souls by tapping it, giving the creature with bloodthirst persist until end of turn
2. Activate Phyrexian Altar by sacrificing the creature with bloodthirst, adding one mana of any color
3. When the creature dies, its persist ability and Dross Scorpion trigger
4. Resolve the persist trigger, returning the creature from your graveyard to the battlefield, which enters the battlefield with at least one +1/+1 counter on it due to its bloodthirst ability
5. Resolve the Dross Scorpion trigger, untapping Cauldron of Souls
6. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite colored mana
• Infinite sacrifice triggers
• Infinite death triggers