Cauldron of Souls, Dross Scorpion, and Workhorse

Prerequisites

• Cauldron of Souls on the battlefield
• Dross Scorpion on the battlefield
• Workhorse on the battlefield

Steps

1. Activate Cauldron of Souls by tapping it, Workhorse gain persist until end of turn
2. Activate Workhorse by removing a +1/+1 counter, adding
3. Repeat from step 2 until Workhorse dies
4. Dross Scorpion and Workhorse triggers
5. Resolve the Dross Scorpion trigger, untapping Cauldron of Souls
6. Resolve the Workhorse persist ability trigger, returning it to the battlefield with three +1/+1 counters on it
7. Repeat

Results

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