At the moment, Ugin, the Spirit Dragon is a good fit and card in general. Decent plus ability and really good minus abilities. Arcane denial might not be worth the two cards your giving your opponent. Clockspinning seems hilarious but might cost more mana then it's worth, though is really good later in the game. i would also try to fit in a basalt monolith because it's a good mana rock and you might need to go infinite with Rings of Brighthearth to play what you want. Mystical,personal ,and enlightened tutor would be good additions as well because of the search and you can stack the top of your library for Narset. That's all i can thing of off the top of my head.
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Thought of another card, Cyclonic rift. Would probably make you a target though.
Never heard of them. I'll be sure to put at least one of them in their. Definitely see them working better then Naturalize.
Rhystic Study seems like it should go in most blue decks. A solid draw card. If you felt like it, you can go infinite mana with pila-pala + Grand Architect and kill opponents by exiling their deck with Oona. You should maybe try to fit a damnation in their too, who knows when you would need it.
^_^