Wish Adventure Mill (Standard)

Primarily we are using Drowned Secrets, Merfolk Secretkeeper // Venture Deeper, and Ashiok, Dream Render to mill down the opponent. Ashiok ensures the permanent element to this process.

Drowned Secrets is the main way we generate value from our cards. Our adventure creatures trigger it twice, plus they are all fairly cheap to play. Lucky Clover is an amazing value play for all adventures and helps make sideboard solutions easier to get out, as well as milling for eight with Venture Deeper. Opt also generates this mill value and Wall of Lost thoughts serves as a fifth and sixth Merfolk Secretkeeper // Venture Deeper, since the card is such a great drop in this deck.

We also run a large amount of answers, with Frogify, So Tiny, Queen of Ice // Rage of Winter, and Thought Collapse all in main deck. Our biggest advantage is the ability to pluck answers from our side board, using the amazing Fae of Wishes // Granted. Keep in mind there's a steep cost of discarding two cards to use the fae's abillity to return to hand; a Run Away Together can do this much more effectively.
Run Away Together works wonders for all of our adventure creatures, and is a great target for Mystic Sanctuary.

Speaking of Fae of Wishes // Granted:
Our side board is entirely focused on disrupting our opponent, with Flood of Tears for board removal, Kasmina, Enigmatic Mentor and God-Pharaoh's Statue for spell taxing, Devious Cover-Up to cycle our best cards for the match up, and of course a Narset, Parter of Veils to prevent card advantage.
Jace, Wielder of Mysteries is a given in most mono blue for the bonus card draw, and his ability to mill the opponent for another two cards per turn doesn't go unnoticed.
Extra sources of Frogify, Lucky Clover, Ashiok, Dream Render, and Queen of Ice // Rage of Winter, are all also in the sideboard, in case Drawn from Dreams isn't enough to pull one of them.
Spark Double gives us a lot of value, doubling up on Kasmina, Ashiok, or Jace is a great idea.
Mass Manipulation is expensive but a great way to close out the game or if nothing else, deal with an especially bad (or useful!) target that Frogify misses.
Selective Snare is functionally a cheaper Flood of Tears, but is limited to countering tribals. This card is great for dealing with knights, elementals, humans, and can even target your own adventure creatures, as they are all wizards.

Note: It's worth mentioning that while So Tiny is a great value card, it gets significantly less useful if ashiok is clearing the graveyard each turn. Consult the Maybeboard for other options if So Tiny isn't living up to your expectations.