I concur. Remove Urza's Factory and consider Vesuva X 4 instead.
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This deck has an exceptionally deadly combo: If you get two Merrow Reejerey's and two Stonybrook Banneret's on the field, and a Summon the School in your hand, you can cast the Summon the School multiple times per turn, growing your Merfolk army exponentially every turn, and four Seahunter's in the deck allow you to go into your deck and find the missing piece(s) of the combo if you need to.