The top combo shown features these four cards:
The explanation for the combo is written,
Result: Infinite damage. Requires: Teshar, Ornithopter, and Blasting Station on the battlefield. Myr Retriever in graveyard. Steps: Cast Ornithopter, triggering Teshar, target Retriever in the graveyard. Untap Blasting Station. Let Ornithopter resolve, then sacrifice it. Sacrifice Retriever to Blasting Station, target an opponent, triggering Retriever, target Ornithopter in the graveyard.
There's a small oversight in that the Ornithopter needs to be in the player's hand at the beginning of the combo in order for the player to cast it, but beyond that, I think this combo--with these specific cards--wouldn't work at all.
The problem is that Blasting Station needs a creature ETB in between every use of its sac ability, and the combo requires that Blasting Station be used twice, with no such trigger in between.
There are plenty of ways to fix this by swapping in a different card for Ornithopter...any X-cost artifact creature that dies immediately on ETB when cast for 0 would do (eg. Walking Ballista or Hangarback Walker), or any 0-cost artifact capable of sacrificing itself (eg. Welding Jar; Urza's Bauble or Mishra's Bauble), but I can't see a way to make the combo work if we're keeping the four cards listed. Casting Ornithopter necessarily puts Ornithopter on the stack before Teshar's ability, meaning that Myr Retriever necessarily arrives on the battlefield before Ornithopter, and if we use Blasting Station to sac Myr Retriever before Ornithopter arrive on the battlefield, then Ornithopter isn't in the graveyard and can't be returned to the player's hand by the Myr Retriever's LTB trigger.
Is there anything I'm missing? Can this combo (with these four specific cards) be made to work?