Havengul Lich + Grimgrin, Corpse-Born + Song of Freyalise + Blight Mound

Havengul Lich

Grimgrin, Corpse-Born

Song of Freyalise

Blight Mound

How it works

1. Activate Grimgrin's ability from Song of Freyalise 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, Blight Mound 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.

This loop transforms your graveyard into a perpetual engine by relying on Havengul Lich to repeatedly cast a creature for a single mana. As that creature is sacrificed to Grimgrin, Corpse-Born, Grimgrin untaps and grows larger while Blight Mound steps in to replace the fallen creature with a Pest token. Meanwhile, Song of Freyalise provides the crucial mana production needed to keep the cycle going through its chapter abilities.