Teshar triggers, returning Scrap Trawler from your graveyard to the battlefield.
Activate Lion's Eye Diamond by discarding your hand and sacrificing it.
Activate Shilgengar by sacrificing Scrap Trawler.
When Scrap Trawler dies, it triggers, returning Lion's Eye Diamond from your graveyard to your hand.
Resolve the Shilgengar ability.
Repeat.
This clever recursion loop begins by casting Lion's Eye Diamond, which triggers Teshar, Ancestor's Apostle to pull Scrap Trawler straight out of your graveyard and onto the battlefield. You then crack the Diamond for mana by discarding your hand, and immediately feed Scrap Trawler to Shilgengar, Sire of Famine's sacrifice ability to fuel your engine. When Scrap Trawler dies, its passive retriever trigger kicks in to bounce the Lion's Eye Diamond right back to your hand, allowing you to replay it and repeat the cycle endlessly. Through this dance, Shilgengar keeps churning out Blood tokens, ultimately letting you amass infinite mana, tokens, and death triggers to overwhelm the table.