Infernal Vessel + Valkyrie's Call + Bloodflow Connoisseur

Infernal Vessel

Valkyrie's Call

Bloodflow Connoisseur

How it works

1. Activate Bloodflow Connoisseur by sacrificing Infernal Vessel.
2. When Infernal Vessel dies, it triggers, returning itself from your graveyard to the battlefield as a Demon in addition to its other types.
3. Resolve the Bloodflow Connoisseur ability.
4. Activate Bloodflow Connoisseur by sacrificing Infernal Vessel.
5. When Infernal Vessel dies, Valkyrie's Call triggers, returning Infernal Vessel from your graveyard to the battlefield as an Angel in additional to its other types.
6. Resolve the Bloodflow Connoisseur ability.
7. Repeat.

This ingenious loop relies on a clever transformation of types to alternate between two separate recursion engines. When you feed Infernal Vessel to Bloodflow Connoisseur for the first time, its own death trigger brings it back as a Demon, ensuring it wasn't an Angel so Valkyrie's Call can step in next time. On the subsequent sacrifice, Valkyrie's Call catches the dying Vessel and returns it to the battlefield as an Angel instead, resetting the condition so Infernal Vessel's own trigger can take over once more. By continuously alternating which static replacement effect brings the Vessel back, Bloodflow Connoisseur feasts on a never-ending cycle of sacrifices to grow infinitely large while triggering any death-based synergies you have in play.