Visionary Augmenter dies, triggering Nim Deathmantle, causing you to pay ({4} magic symbol) to return Visionary Augmenter from your graveyard to the battlefield, and attach Nim Deathmantle to it.
Visionary Augmenter enters the battlefield, creating two 1/1 Servo creature tokens.
Activate Ashnod's Altar by sacrificing a Servo, adding ({C} magic symbol) ({C} magic symbol) .