Shilgengar, Sire of Famine + Grazing Kelpie + Hardened Academic

Shilgengar, Sire of Famine

Grazing Kelpie

Hardened Academic

How it works

1. Activate Shilgengar 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. Resolve the Shilgengar ability.
5. Repeat.