Nim Deathmantle + Ashnod's Altar + Xorn + Plundering Barbarian

Nim Deathmantle

Ashnod's Altar

Xorn

Plundering Barbarian

How it works

1. Activate Ashnod's Altar by sacrificing Plundering Barbarian, adding CC.
2. Plundering Barbarian dies, triggering Nim Deathmantle, causing you to pay 4 to return Plundering Barbarian from your graveyard to the battlefield, and attach Nim Deathmantle to it.
3. Plundering Barbarian enters the battlefield, creating two Treasure tokens.
4. Activate two Treasure tokens by tapping and sacrificing those, adding two mana of any color.
5. Repeat.