Activate Spawning Pit's second ability by paying ({1} magic symbol) and removing two charge counters from it, creating two 2/2 Spawn artifact creature tokens.
Activate Spawning Pit's first ability by sacrificing a Spawn.
The Spawn dies, triggering Pitiless Plunderer, creating two Treasure tokens.
Resolve the Spawning Pit ability, putting two charge counters on it.
Activate a Treasure by tapping and sacrificing it, adding ({1} magic symbol) .