Tarrian's Soulcleaver + Herd Baloth + Altar of Dementia

Tarrian's Soulcleaver

Herd Baloth

Altar of Dementia

How it works

1. Put a +1/+1 counter on Herd Baloth.
2. Herd Baloth triggers, creating a 4/4 Beast creature token.
3. Activate Altar of Dementia by sacrificing the Beast.
4. When the Beast dies, Tarrian's Soulcleaver triggers, putting a +1/+1 counter on Herd Baloth.
5. Herd Baloth triggers, creating a 4/4 Beast creature token.
6. Resolve the Altar of Dementia ability, causing target player to mill cards equal to the sacrificed creature's power.
7. Repeat from step 3.

This ingenious loop turns a simple counter mechanic into a devastating engine by weaving together creature generation and sacrifice. It all hinges on Herd Baloth, which acts as our token factory by spawning a 4/4 Beast whenever it receives a +1/+1 counter. When that fresh Beast is fed to Altar of Dementia, its death sends it to the graveyard, which immediately wakes up Tarrian's Soulcleaver to drop another +1/+1 counter right back onto Herd Baloth. Because the Soulcleaver triggers off any artifact or creature dying, sacrificing the Beast restarts the whole sequence, letting you mill out any opponent an infinite number of times.