So this seems like it could be really, REALLY useful in the new hangarback walker/arcbound ravager decks. Since their is not negative casting costs in magic (as far as I know), this card could lead to infinite loops with memnites, lotus petals, mox opals, etc etc. I might be wrong on that, not sure, but either way, anytime you sac anything you should be able to get hangarback walkers back on hand. Seems some good.
While someone more clever and experienced with Shops is likely to come up with better, the first thing I think of is recurring any artifact in your deck with Metalwork Colossus. So my thought is to go in the opposite direction (even more prison based) and create a stronger lock by keeping tangle wire set at 4 with smokestack in play, for example.
Also, the value of cards like Spine of Ish-Shah goes up in that case, as do other silver bullets, so my deckbuilding would be steered toward the new prison lists featuring Inventor's Fair.
Thinking an engine through.
Cathodion, Trawler and Metalwork Colossus in play. Metalwork Colossus and Lotus in the GY.
Sac the Cathodion, and colossus, get back colossus.
Trawler trigger from colossus gets you Cathodion back.
Trawler trigger from Cathodion gets you Lotus.
Cast Cathodion, lotus and colossus.
Kill with pyrite spell bomb?
This sounds strictly worse than Salvagers except that it works though 2 thorns.