Mikaeus, the Unhallowed, River Kelpie, and Viscera Seer

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• River Kelpie on the battlefield
• Viscera Seer on the battlefield

Steps

1. Activate Viscera Seer by sacrificing River Kelpie
2. River Kelpie's persist and undying abilities trigger
3. Resolve the persist trigger, returning River Kelpie from your graveyard to the battlefield with a -1/-1 counter on it
4. River Kelpie enters the battlefield, causing you to draw
5. The undying trigger fails to resolve because River Kelpie is not in your graveyard
6. Resolve the Viscera Seer trigger, scrying 1
7. Activate Viscera Seer by sacrificing River Kelpie
8. River Kelpie's undying and persist abilities trigger
9. Resolve the undying trigger, returning River Kelpie from your graveyard to the battlefield with a +1/+1 counter on it
10. River Kelpie enters the battlefield, causing you to draw a card
11. The persist trigger fails to resolve because River Kelpie is not in your graveyard
12. Resolve the Viscera Seer trigger, scrying 1
13. Repeat

Results

• Infinite card draw
• Near-infinite death triggers
• Near-infinite ETB
• Near-infinite LTB
• Near-infinite sacrifice triggers
• Near-infinite scry 1