Nim Deathmantle + Ashnod's Altar + Xorn + Brazen Freebooter

Nim Deathmantle

Ashnod's Altar

Xorn

Brazen Freebooter

How it works

1. Activate Ashnod's Altar by sacrificing Brazen Freebooter, adding CC.
2. Brazen Freebooter dies, triggering Nim Deathmantle, causing you to pay 4 to return Brazen Freebooter from your graveyard to the battlefield, and attach Nim Deathmantle to it.
3. Brazen Freebooter 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.