Mikaeus, the Unhallowed, Defiant Greatmaw, and Yahenni, Undying Partisan

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Defiant Greatmaw on the battlefield
• Yahenni, Undying Partisan on the battlefield
• Defiant Greatmaw does not have a +1/+1 counter on it

Steps

1. Activate Yahenni by sacrificing Defiant Greatmaw
2. When Defiant Greatmaw dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. When Defiant Greatmaw enters the battlefield, its first ability triggers, putting two -1/-1 counters on it
4. Defiant Greatmaw's second ability triggers, removing a -1/-1 counter from another creature you control
5. Resolve the Yahenni ability from step 1, causing it to gain indestructible until end of turn
6. Repeat

Results

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