Teshar triggers, returning Scrap Trawler from your graveyard to the battlefield.
When Scrap Trawler enters, Blasting Station triggers, untapping Blasting Station.
Activate Tormod's Crypt by tapping and sacrificing it.
Activate Blasting Station by tapping it and sacrificing Scrap Trawler.
When Scrap Trawler dies, it triggers, returning Tormod's Crypt from your graveyard to your hand.
Resolve the Blasting Station ability.
Repeat.
This clever loop harnesses Teshar, Ancestor's Apostle and Scrap Trawler to turn cheap artifacts into an endless engine of recursion. By casting Tormod's Crypt, you trigger Teshar to pull Scrap Trawler straight back from the graveyard, which in turn untaps Blasting Station via its own entry trigger. You then sacrifice Scrap Trawler to Blasting Station to deal damage, triggering Scrap Trawler to return Tormod's Crypt to your hand so the whole cycle can begin anew.