You had me at Mystical Teachings for Through the Breach. You lost me at Memnite.
What the hell is going on here?
The goal of riverotter's deck, like so many combo-control decks before it, is to live just long enough to find their combo. In this case, the combo involves Possibility Storm, finding your lone Memnite via Tolaria West, and Storming up an Emrakul, the Aeons Torn. If your Memnite is ever discarded, you can use Izzet Charm to discard Emrakul and shuffle it back in. In a pinch, you could also transmute for the Zoetic Cavern.
If that is a little too slow or you're facing down a mountain of disruption, there's always the Through the Breach backup plan. The beauty of combo-control is that it's not the fastest combo on the block, but it's very resilient, and having a backup plan further enforces that.
While the deck might be going a little too deep on the Tolaria West package (I'm looking at you, Mouth of Ronom), and could certainly be cleaned up a bit, I like the look of it. Ignoring discard, there's not much I'd be scared to play against.
Aside from the manabase, I'd be interested in adding some more Cryptic Commands. When you're trying to survive long enough to assemble your combo, Fog plus draw a card is pretty good. The sideboard is also wonky, but it looks like riverotter has a plan. I'm just not sure what it is.