Cauldron of Souls, Deceiver Exarch, Grimgrin, Corpse-Born, Haunted One, and Vohar, Vodalian Desecrator

Prerequisites

• Cauldron of Souls on the battlefield
• Deceiver Exarch on the battlefield
• Grimgrin, Corpse-Born on the battlefield
• Haunted One on the battlefield
• Vohar, Vodalian Desecrator on the battlefield
• Vohar is your commander and does not have summoning sickness
• Deceiver Exarch does not have a +1/+1 counter on it

Steps

1. Activate Vohar's first ability by tapping it
2. Vohar triggers, giving creatures you control that share a creature type with it +2/+0 and undying until end of turn
3. Resolve the Vohar ability from step 1, causing you to loot
4. Activate Grimgrin by sacrificing Deceiver Exarch
5. When Deceiver Exarch dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
6. When Deceiver Exarch enters the battlefield, it triggers, untapping Cauldron of Souls
7. Resolve the Grimgrin ability from step 4, untapping it and putting a +1/+1 counter on it
8. Activate Cauldron of Souls by tapping it, giving Deceiver Exarch persist until end of turn
9. Activate Grimgrin by sacrificing Deceiver Exarch
10. When Deceiver Exarch dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
11. When Deceiver Exarch enters the battlefield, it triggers, untapping Vohar
12. Resolve the Grimgrin ability from step 9, untapping it and putting a +1/+1 counter on it
13. Repeat

Results

• Infinite card draw
• Infinite draw triggers
• Infinite looting
• Near-infinite +1/+1 counters on Grimgrin
• Near-infinite death triggers
• Near-infinite ETB
• Near-infinite LTB
• Near-infinitely powerful Phyrexians, Merfolks and Wizards you control until end of turn
• Near-infinite sacrifice triggers