In a format with a large card pool, eventually something will be printed that's another piece to a combo deck. And here we are.
Puresteel Paladin decks have always been about drawing its namesake card. If it didn't, it probably couldn't win otherwise. Now that's not the case, thanks to Monastery Mentor. While Puresteel Paladin might allow you to draw your deck, Monastery Mentor should allow you to create an army and potentially attack for way more than lethal next turn if you have a Retract. Grapeshot allows you to kill someone without an attack step, and Echoing Truth is there to remove something like a Runed Halo or Leyline of Sanctity if necessary.
This deck is obviously fragile, but it does have Muddle the Mixture to search for Puresteel Paladin, and Noxious Revival to return a countered, killed, or discarded combo piece. It also doesn't require much to win, so I could easily see the deck win after a mulligan or two.
The sideboard could probably use some help, but it also can't sideboard in a ton of cards without diluting the deck. Still, I think we can do better against Splinter Twin than Batwing Brume. Spellskite might be a nice card that serves several purposes.