Mikaeus, the Unhallowed, River Kelpie, and Carrion Feeder

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• River Kelpie on the battlefield
• Carrion Feeder on the battlefield

Steps

1. Activate Carrion Feeder by sacrificing River Kelpie
2. When River Kelpie dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. When River Kelpie enters, its first ability triggers, causing you to draw a card
4. Resolve the Carrion Feeder ability
5. Activate Carrion Feeder by sacrificing River Kelpie
6. When River Kelpie dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
7. When River Kelpie enters, its first ability triggers, causing you to draw a card
8. Resolve the Carrion Feeder ability
9. Repeat

Results

• Infinite card draw
• Infinite draw triggers
• Near-infinite +1/+1 counters on a creature
• Near-infinite ETB
• Near-infinite LTB
• Near-infinite death triggers
• Near-infinite sacrifice triggers