The Master, Formed Anew, Cavalier of Night, and Grimgrin, Corpse-Born

Prerequisites

• The Master, Formed Anew on the battlefield
• Cavalier of Night in exile
• Grimgrin, Corpse-Born on the battlefield
• available

Steps

1. Activate Grimgrin by sacrificing The Master
2. When The Master dies, its second ability triggers, returning itself from your graveyard to the battlefield as a copy of Cavalier of Night
3. Resolve the Grimgrin ability, putting a +1/+1 counter on it
4. When The Master enters the battlefield, its first ability triggers, doing nothing
5. Repeat

Results

• Infinite +1/+1 counters on a creature
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers