Havengul Lich + Grimgrin, Corpse-Born + Relic of Legends + Open the Graves

Havengul Lich

Grimgrin, Corpse-Born

Relic of Legends

Open the Graves

How it works

1. Activate Relic of Legends's last ability by tapping Grimgrin, adding one mana.
2. Activate Grimgrin by sacrificing the creature castable for one mana, untapping Grimgrin and putting a +1/+1 counter on it.
3. When that creature dies, Open the Graves triggers, creating a creature token or a token that adds mana.
4. If you created a creature token, repeat steps 1 and 2 to sacrifice that token and add an additional mana.
5. If you created a token that adds mana, instead activate that token to add mana.
6. Activate Havengul Lich by paying 1, allowing you to cast the sacrificed creature from your graveyard this turn.
7. Cast that creature from your graveyard by paying one mana.
8. Repeat.