Activate Ashnod's Altar by sacrificing Lord Skitter's Butcher, adding ({C} magic symbol) ({C} magic symbol) .
When Lord Skitter's Butcher dies, Nim Deathmantle triggers, causing you to pay ({4} magic symbol) to return Lord Skitter's Butcher from your graveyard to the battlefield, and attach Nim Deathmantle to it.
When Lord Skitter's Butcher enters the battlefield, it triggers, creating a 1/1 Rat creature token.
Activate Ashnod's Altar by sacrificing the Rat, adding ({C} magic symbol) ({C} magic symbol) .