Welcome to the Mill.
I've been playing this deck for about 3 years. Shortly after the banning of Splinter Twin I only play at my LGS which is actually a 30 min drive so not to local. My LGS is pretty competitive. A lot of tier 1-2 decks. Being the only one there that runs mill gives me an advantage. Most sideboards aren't prepared for it.
The Deck Staples:
Archive Trap Mills 13 off a fetch land. With a format heavy in fetches its always good to see in the opening hand or in the first few draws.
Hedron Crab More of a Mill spell than a creature. If he sticks on the board for a few turns he can mill sometimes more than Archive Trap. Turns our fetches into mill 6. With multiple crabs it ends games real fast.
Glimpse the Unthinkable the best mill card ever printed, 10 cards for 2 mana. Not much more to say.
Mesmeric Orb comes down early, gets around hexproof, (leylines and witchbane orbs) milling my own deck isnt that bad since it gives me options with Mission Briefing. also very good vs lantern control and untap heavy decks like control.
Ashiok, Dream Render Newest PW from WOTS, Shuts off fetchs, and tutoring exiles yards. Can interfere with Visions of beyond but benefits out weigh the chances of that happening. Poops on Tron, Scapeshift, Chord/Neoform, slow start dredge, can give you a shot vs maindeck emrakuls. The Exile effect also gets around Leyline of Sanctity
Removal Package
Early Game
Fatal Push Kills most threats in modern, revolt trigger shouldnt be to hard to do based on our fetches and crab bait
Collective Brutality kills 2/2's, makes opponent discard (also keeps hand size down for Ensnaring Bridge if needed), and gains us life which is crucial for burn and aggro matches.
Surgical Extraction just because i need to be able to stop combo decks and remove certain threats as soon as a copy hits the gy.
Late Game
Mission Briefing our decks better version of Snapcaster Mage only because of the free casting of archive traps. Since snappy made them cast as flashback spell which would never work for total 7 mana. Mes Orb fills your yard with good spells and the best things to recast were usually visions, or another mill spell. this is better from mid to late game when your choices in the yard are plentiful.
Support Cards
Ensnaring Bridge Keeps us from getting crushed by big guys like Death's Shadow Gurmag Angler Tarmogoyf. Some decks cant beat it MB so it has its times where it just wins you the game.
Trapmaker's Snare tutors archive traps at instant speed. so its kinda like a 2 mana archive trap. usually a first cut in sideboarding depending on the match.
Crypt Incursion lets me gain a pretty large amount of life with creatures that are in the graveyard. Crushes dredge.
Visions of Beyond Card Advantage if we get 20 in the yard. Had a few games where i was able to turn 1 visions for 3 with the help of a pair of archive traps. Then refill the hand. Careful when drawing 3 if you need ensnaring bridge to be effective. You can run Thought Scour here if you want. The advantage it has in some matchups like control when you can mess with their scrys at instant speed is useful.
Field of Ruin Helps in tron and valakut matches. Forces them to search so it makes it a 3 mana Archive Trap triggers landfall on crab.
Lands are split between 8 fetches and dual lands with enough basics to play under Blood Moon
Oboro, Palace in the Clouds great with crabs and no other lands to play. also triggers revolt if needed for Fatal Push
SIDEBOARD
Echoing Truth Just tempo card that can help us interact with Leyline of Sanctity and walkers. Its most just to buy time to finish the game.
Profane Memento brought in vs zoo style decks and creature heavy matches.
Bontu's Last Reckoning just another wrath effect for more aggro games like elves or goblins. also catches some people off guard like. "i was figuring you had Damnation"
Torpor Orb good vs humans, spirits, (spell queller in particular) and hardened affinty. all not so good matches.
Unmoored Ego Great for milling cards that surgical cant get because there isn't a copy in the yard. A way around cards like Nexus of Fate, Emrakul, the Aeons Torn Elixir of Immortality
then just some extra copies of MB cards for specific matchups.