Knotvine p[aladin seems like a good fit for your deck
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Put 2-3 Jace in, Forced Fruition seems like it could be more devastating than memory erosion.I like your choice in counter spells, summon the school seems kind of weak. -4 Witsniper ( Popping just the top card seems really weak) -4 Initiate (I tried playing with this before sometimes you just Can't spend mana to do the ability.) +1 Drowner of Secrets ( Best Merfolk Mill Spell you can play) -X Judge of currents ( Four seems to much I would reccomend cutting down two to three) Harbinger ( I don't like her but it looks like you might NEED her) +4 Merrow Reejerey ( Awesome card that can get an infinite loop to mill the opponent to death. With secrets, summon the school, and three reejereys) +4 Stonybrook Banneret ( Make my spells cheaper ohthello's YEAH!) +4 Silver Gill adept ( Drawing cards will help you get your deck flowing) +3 Ponder ( See above) I have more fixes this is just a big comment already.
Kathari Remnant Might be very good in this deck. Cascade into Jace, Mind funeral, Boomerang, Memory Sluice, You might need to tinker around with the spells a bit to not catch counter spells. IE Cryptic Command, Soul Manipulation etc.