Havengul Lich, Grimgrin, Corpse-Born, Relic of Legends, and Cathodion

Prerequisites

• Havengul Lich on the battlefield
• Grimgrin, Corpse-Born on the battlefield
• Relic of Legends on the battlefield
• Cathodion on the battlefield

Steps

1. Activate Grimgrin by sacrificing Cathodion, untapping Grimgrin and putting a +1/+1 counter on it
2. When Cathodion dies, it triggers, adding mana equal to its casting cost
3. Activate Relic of Legends's ability by tapping Grimgrin, adding one mana
4. Activate Havengul Lich by paying , allowing you to cast Cathodion from your graveyard this turn
5. Cast Cathodion from your graveyard by paying its casting cost
6. Repeat

Results

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