My suggestion would be to add another imperious smite instead of a Purification filter (having 2 of each card is better for consistency I think). Also, Radiant dawn is so good I always run 2x of it in my decks -- maybe take out Helios Guardian as this card has a tendency to backfire on you as it randomly buffs a creature (including your opponents').

Lysander's honor is great for control decks but I think your build is suited for more of an aggro playing style so maybe Summon Acolyte will be a better choice.

Overall this is an interesting build and would like to see your progress using this deck in the coming days.