Cauldron of Souls, Dross Scorpion, and Extruder

Prerequisites

• Cauldron of Souls on the battlefield
• Dross Scorpion on the battlefield
• Extruder on the battlefield
• You control another artifact creature with base toughness 2 or greater
• Extruder does not have a -1/-1 counter on it

Steps

1. Activate Cauldron of Souls by tapping it, giving Extruder and the other artifact creature with base toughness 2 or greater persist until end of turn
2. Activate Extruder by sacrificing it, targeting the other artifact creature
3. When Extruder dies, its persist ability and Dross Scorpion trigger
4. Resolve the Dross Scorpion trigger, untapping Cauldron of Souls
5. Resolve the Extruder trigger, returning it from your graveyard to the battlefield with a -1/-1 counter on it
6. Resolve the Extruder ability from step 2, putting a +1/+1 on the targeted creature
7. Activate Extruder by sacrificing the other artifact creature, targeting Extruder
8. When the creature dies, its persist ability and Dross Scorpion triggers
9. Resolve the Dross Scorpion trigger, untapping any artifact you control
10. Resolve the persist trigger, returning the creature from your graveyard to the battlefield with a -1/-1 counter on it
11. Resolve the Extruder ability, putting a +1/+1 counter on it
12. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite mana artifacts you control can produce
• Infinite untap of artifacts you control