Praxis pledge aggro/mid

So, I've been loving pledge praxis, and this is the best build I've found so far. I started trying to do a more traditional ramp/big unit build, and it just felt bad, so then I switched to teacher of humility and amaran stinger and went up to 4 gun runner. This deck feels like it has real potential, and there are tons of great synergies like teacher+stinger and darya + gunrunner. Shatterglass mages are generally pretty good, but have been worse since I've stopped seeing permafrost (thanks palace). Some things that I am on the fence about: Heart of the vault in the market is good, but I've had a suggestion to change it to jawbone greatsword, even though it doesn't curve well into gunrunner. Xenan Obelisk is nice so that you don't over extend into harsh rule, and goes great with amaran stinger, but I'm not sure if it is worth. Also, it is possible that auralian merchant would better fit the deck, but I doubt it. Also, playing some purify's main deck could be worth it, depending on how many silverwing couriers you see. I would really love any inputs about this deck and how people think it could be made better. I made it to masters pretty easily with it, and it feels good to pilot.