Cauldron of Souls, Dross Scorpion, Arsenal Thresher, and Ashnod's Altar

Prerequisites

• Cauldron of Souls on the battlefield
• Dross Scorpion on the battlefield
• Arsenal Thresher on the battlefield
• Ashnod's Altar on the battlefield
• You have at least one artifact card in hand
• Arsenal Thresher does not have a -1/-1 counter on it

Steps

1. Activate Cauldron of Souls by tapping it, giving Arsenal Thresher persist until end of turn
2. Activate Ashnod's Altar by sacrificing Arsenal Thresher, adding
3. When Arsenal Thresher dies, its persist ability and Dross Scorpion trigger
4. Resolve the Dross Scorpion trigger, untapping Cauldron of Souls
5. Resolve the Arsenal Thresher trigger, returning it from your graveyard to the battlefield with a -1/-1 counter on it, and then choosing to reveal at least one artifact card from your hand to remove the -1/-1 counter
6. Repeat

Results

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