Activate Ashnod's Altar by sacrificing Ancient Adamantoise, adding CC.
When Ancient Adamantoise dies, it and Nim Deathmantle trigger.
Resolve the Nim Deathmantle trigger, causing you to pay 4 to return Ancient Adamantoise from your graveyard to the battlefield and attach Nim Deathmantle to it.
Resolve the Ancient Adamantoise trigger, creating ten Treasure tokens that enter untapped due to Archelos.
Resolve the Ashnod's Altar ability.
Activate two Treasures by tapping and sacrificing them, adding 2.