Wait, yesterday was Tuesday? For the first time in a long time, I honestly completely forgot I needed to write a blogpost. Sigh.
Right off the bat, this is a pretty big creature for Blue. While it looks expensive at 5U, even if you only have a single Artifact in play, a 4/4 for 4U is perfectly reasonable. With almost 60 difference Artifacts at Common in Standard right now, you should have no problem finding options for almost any Blue-based archetype. However, what makes this card so good is the fact that it also has Hexproof. In the current metagame, creatures are much less important due to how many good options there are for removal. Bastion Inventor sidesteps all of that. Even better, Hexproof takes most of the risk out of creature Auras or Equipment. Give it Flying with Ghostly Wings, or attach Inventor's Goggles on it for free when it enters the battlefield, and you have quite the potent threat.
Generally speaking, Hexproof is one of the better evergreen abilities in Standard Pauper, and in this particular case you're getting it on a creature that is already pretty strong. Bastion Inventor is a great threat for any Blue-based midrange deck or a superb finisher for a Blue-based Control deck. I have no doubt this is going to make a big impact on the format.
Want to know more about what I think of the cards in Aether Revolt? Check out Part One of my Standard Pauper review over at PureMTGO.