I run Oblivion Stone. I like it more than vault because of the option to sink mana into saving your stuff and because I don't want too much removal to be exile. I also like it more than disk because it topdecks a lot better and kills walkers.
Rachet Bomb and Powder Keg are both sweet. Keg is a little more narrow in what it hits but I'm also running almost every creature land and it can shut those off in a pinch.
I like Engineered Explosives quite a bit. A great Trinket Mage target and easy to return with Scrap Trawler. The lower cmc of your creature suite, the better....it also gets better with a greater density of tokens. I think of it like a colorless Pyroclasm.
I really like engineered explosives. It has a lot of play to it and requires careful play to get the most out of it. You do need a mana base that supports it - I have vivids and tri lands. There's also other cool artifact synergy too. Eg.
I also ring disk. I like that it gives your opponent the opportunity to remove it, so let's done counterplay. I don't have many planeswalkers so it's more difficult to abuse that way.