Mikaeus, the Unhallowed, River Kelpie, and Yahenni, Undying Partisan

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• River Kelpie on the battlefield
• Yahenni, Undying Partisan on the battlefield

Steps

1. Activate Yahenni 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 Yahenni ability
5. Activate Yahenni 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 Yahenni ability
9. Repeat

Results

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