Serrated Biskelion, Thornbite Staff, Thran Vigil, Ashnod's Altar, and Butcher Ghoul

Prerequisites

• Serrated Biskelion on the battlefield
• Thornbite Staff on the battlefield
• Thran Vigil on the battlefield
• Ashnod's Altar on the battlefield
• Butcher Ghoul on the battlefield
• Serrated Biskelion does not have summoning sickness
• Thornbite Staff attached to Serrated Biskelion
• Butcher Ghoul does not have more than one +1/+1 counter on it

Steps

1. Activate Serrated Biskelion by tapping it, putting a -1/-1 counter on it and Butcher Ghoul
2. Activate Ashnod's Altar by sacrificing Butcher Ghoul, adding
3. When Butcher Ghoul dies, its undying ability and Serrated Biskelion trigger
4. Resolve the Serrated Biskelion trigger, untapping it
5. Resolve the Butcher Ghoul trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it
6. When Butcher Ghoul leaves your graveyard, Thran Vigil triggers, putting a +1/+1 counter on Serrated Biskelion
7. Repeat

Results

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