Ashnod's Altar + Grazing Kelpie + Hardened Academic

Ashnod's Altar

Grazing Kelpie

Hardened Academic

How it works

1. Activate Ashnod's Altar 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. Hardened Academic triggers, putting a +1/+1 counter on Grazing Kelpie.
4. Repeat.

This loop relies on an ingenious engine that continually neutralizes its own drawbacks to generate infinite colorless mana and trigger counts. By using Ashnod's Altar to sacrifice Grazing Kelpie, you not only harvest raw mana, but also trigger its persist ability to bring it back with a hindering -1/-1 counter. This is where Hardened Academic earns its keep: whenever Grazing Kelpie leaves the graveyard, the Academic steps in to place a +1/+1 counter on it, which instantly annihilates the -1/-1 counter through state-based actions. With the slate wiped clean every single cycle, you can endlessly repeat the sacrifice to fuel your engine without the creature ever getting permanently locked down by its own counters.