Prototype Portal, Dross Scorpion, Shilgengar, Sire of Famine, and Cathodion

Prerequisites

• Prototype Portal on the battlefield
• Dross Scorpion on the battlefield
• Shilgengar, Sire of Famine on the battlefield
• Cathodion on the battlefield
• available

Steps

1. Activate Prototype Portal by paying and tapping it, creating a token copy of Cathodion
2. Activate Shilgengar by sacrificing Cathodion
3. When Cathodion dies, Cathodion and Dross Scorpion trigger
4. Resolve the Cathodion trigger, adding
5. Resolve the Dross Scorpion trigger, untapping Prototype Portal
6. Resolve the Shilgengar ability, creating a Blood token
7. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite Blood tokens