Might I suggest going up to 23 lands. This deck has a pretty high curve and I can guarantee you will get mana screwed at least half the time.
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With so many 2 drops, maybe consider running thrull parasite over the screecher or syndic? Or is there a reason you prefer these over parasite?
Elvish piper by any chance?
How does this deck kill the opponent?
While I personally like proliferate decks a lot, I am curious of what prevents this deck from being rushed at during the first few turns? I only ask because the only two drops are contagion clasps.