Activate Altar of Dementia by sacrificing Fiend Hunter.
When Fiend Hunter dies, its second ability triggers, returning Hero of the Dunes to the battlefield from exile.
When Hero of the Dunes enters the battlefield, it triggers, returning Fiend Hunter from your graveyard to the battlefield.
When Fiend Hunter enters the battlefield, its first ability triggers, exiling Hero of the Dunes.
Resolve the Altar of Dementia ability from step 1, causing target player to mill cards equal to Fiend Hunter's power.
Repeat.
This loop relies on a clever recursion cycle between **Hero of the Dunes** and **Fiend Hunter** to endlessly grind down your opponents. Whenever **Hero of the Dunes** enters the battlefield, its triggered ability plucks **Fiend Hunter** right back out of your graveyard, which in turn triggers its own entry ability to exile **Hero of the Dunes** until it leaves. **Altar of Dementia** acts as the engine for this continuous flicker, letting you sacrifice **Fiend Hunter** to mill a target player for cards equal to its power—boosted, naturally, by the static +1/+0 anthem granted by **Hero of the Dunes** to creatures of its size. Repeating this cycle yields infinite sacrifices, entries, leaves, and a mountain of milled cards to seal the game.