Havengul Lich + Grimgrin, Corpse-Born + Citanul Hierophants + Golgari Germination

Havengul Lich

Grimgrin, Corpse-Born

Citanul Hierophants

Golgari Germination

How it works

1. Activate Grimgrin's ability from Citanul Hierophants 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, Golgari Germination 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.