Activate Fain's first ability by tapping it and sacrificing Tenacious Dead.
Tenacious Dead dies, triggering itself and Fain.
Resolve the Fain trigger, untapping it.
Resolve the Tenacious Dead trigger, causing you to pay ({1} magic symbol) ({B} magic symbol) to return it from your graveyard to the battlefield tapped.
Resolve the Fain ability from step 1, putting two +1/+1 counters on Crystalline Crawler.
Activate Crystalline Crawler's first ability twice by removing two counters from it, adding ({B} magic symbol) ({B} magic symbol) .