U Mill (Standard)

Milling is a time-honored way of winning with jank in MTG. To this end, I've developed this list.
<b>Card Choices</b>
Thought Collapse and Didn't Say Please: Both are counterspells for things that may afford the opponent an ability to win the game.
Merfolk Secretkeeper: a one-mana 0/4 that has an attached mill spell.
Brazen Borrower: One of the best pieces of interaction for threats that hit the field before we get shields up.
Vantress Gargoyle: Alternate win condition. We can cast this on T4/T5 and have counter mana up for anything they want to do about it.
Negate: Come on, planeswalkers are a thing.
Drowned Secrets: All-in on the mill plan with this enchantment
Ashiok: For decks that like returning things from the graveyard, it's excessively hard if they have no graveyard.
Gadwick: Card-draw, I'm not sure he belongs here, but for testing I'll keep him.
Into the Story: You'll almost always be casting this for less mana because they're likely to have more than seven cards in their graveyard.

Looking for sideboard suggestions, if anyone wanders across this post.