Altar of Dementia + Grazing Kelpie + Hardened Academic

Altar of Dementia

Grazing Kelpie

Hardened Academic

How it works

1. Activate Altar of Dementia 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 Altar of Dementia ability.
5. Repeat.