"Pia's Revolution: They will return."
Virgilio F. De leon Jr. MD
Pia's Revolution makes me look forward to Aether Revolt and it is because of this specific scenario: With the 3 mana cost red enchantment in play , you cast an Emerging Elder Deepfiend , sacrificing a Metalwork Colossus that you were able to cast for free because of it's "Selective Affinity". You will then ask your opponent if you would let the Metalwork Colossus back into your hand since it landed on your graveyard. So two things will happen , your opponent could say Yes and the Metalwork Colossus comes back to your hand where you can cast it again for free or they could say no and Pia's Revolution will deal 3 damage to him or her. Opponents with tons of life would rather say No rather than face another 10/10 monster on the battlefield. However their ordeal is not yet over because you can still sacrifice 2 artifacts, like a Prophetic Prism to get the Colossus back. Now , for each of those sacrificed artifacts you need to ask if they will also come back to your hand or it's 3 damage for each. No opponent would allow 9 points of damage(including the 3 earlier) unless they have many more life points to spare.
Now assuming that you 2 Foundry Inspectors in play you could cast your Prophetic Prism for free and draw cards in the process. You could say that I would add this to my existing Metalwork Colossus deck the moment I get it. With this in play any board wipe or artifact destruction would mean you could have the chance to get the destroyed artifact or deal more damage.
A more evil combo would be to sacrifice a Scrap Trawler and it would also get you an artifact in the graveyard and return it to your hand. This seems like a great piece for some sort of engine but I can't put my finger on it.