Stalwart Successor, Trapjaw Kelpie, and Yahenni, Undying Partisan

Prerequisites

• Stalwart Successor on the battlefield
• Trapjaw Kelpie on the battlefield
• Yahenni, Undying Partisan on the battlefield

Steps

1. Activate Yahenni by sacrificing Trapjaw Kelpie When Trapjaw Kelpie dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
2. When Trapjaw Kelpie enters, Stalwart Successor triggers, putting a +1/+1 counter on Trapjaw Kelpie Resolve the Yahenni ability
3. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers