I feel like Ephara, God of the Polis is a little not very tempo-y because of the devotion and the sub par ability in your strat. I can see what your trying to do with blinking Ojutai Exemplars, but it seems like to much mana to pull that combo effectively in an early mid range deck. Plus its not like you don't have easy card draw when your filling up your graveyard. So I would suggest taking out the god and getting some more protection. This brings up the question; Feat of Resistance, another Valorous Stance, or two Gods Willing? I think gods willing is the best because of the scry to set up more effective Anticipates and such. It's also one mana which can be a game changer. Hope this was helpful, +1 check out my decks.

Might I recommend sideboarding Glare of Heresy? Playing UW myself the main issue I have is removing problematic planeswalkers (Elsabeth, Sorin, Narset). Luckily all of them have white.

I've updated the board slightly since this decklist was built. I've updated it.