Activate Ashnod's Altar by sacrificing Armada Wurm, adding ({C} magic symbol) ({C} magic symbol) .
Armada Wurm dies, triggering Nim Deathmantle, causing you to pay ({4} magic symbol) to return Armada Wurm from your graveyard to the battlefield, and attach Nim Deathmantle to it.
Armada Wurm enters the battlefield, creating a 5/5 Wurm creature token.
Activate Ashnod's Altar by sacrificing the Wurm, adding ({C} magic symbol) ({C} magic symbol) .