Thran Vigil + Bloodflow Connoisseur + Grazing Kelpie

Thran Vigil

Bloodflow Connoisseur

Grazing Kelpie

How it works

1. Activate Bloodflow Connoisseur by sacrificing Grazing Kelpie.
2. When Grazing Kelpie dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Thran Vigil triggers, putting a +1/+1 counter on Grazing Kelpie.
4. Resolve the Bloodflow Connoisseur ability.
5. Repeat.

This clever loop relies on Grazing Kelpie's persist ability to bring itself back from the dead, which naturally leaves the graveyard and immediately triggers Thran Vigil to place a +1/+1 counter on a creature you control. Because state-based actions cause that newly arrived +1/+1 counter to instantly annihilate the -1/-1 counter left by persist, the Kelpie is completely cleared and ready to be sacrificed all over again to Bloodflow Connoisseur. As you feed the Kelpie to the Connoisseur over and over, you continuously generate infinite sacrifices, enters-the-battlefield triggers, and endless growth for your creatures.