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