Dimir Mill is one of my favourite strategies and it never stops being fun to watch your opponent's deck shrink, even after years :) I have been playing this deck for a very long time and I can say that I am very satisfied with this version. The cards harmonize perfectly with each other so that it can even hold its own against other competitive modern decks like Jund, Mono Red/Burn and Death's Shadow. I would be very happy about suggestions for improvement and opinions ;)

Main idea:

Obviously mill the opponent until he runes out of cards :)

Protection:

Use Drown in the Loch to counter spells or destroy creatures.Fatal Push is also a good solution to deal with single creatures. Likewise, Ensnaring Bridge prevents your opponent from attacking you with large creatures later in the game. Another good card is Crypt Incursion which generates life in case it goes down too fast ;) (very important against aggro decks) Last but not least there is Surgical Extraction which removes the cards we can't handle from the opponent and also gives us a glimpse of the opponent's hand as it turned out to be very helpful for me ;)

Mill:

Let's move on to the cards that make my opponent die of card death :) For this we have creatures, sorceries, instants and artefacts at our disposal. In the creature area, Hedron Crab and Ruin Crab ensure that 3 cards each are milled by our lands that enter the board. On turn two, that can be 12 cards flying into the opponent's graveyard in the best case :) In general, the longer the crabs are in play, the more dangerous and annoying they become for the opponent. For the sorceries that mill our opponent, we have Glimpse the Unthinkable and Maddening Cacophony. Good mill cards for 2 mana, but I think Maddening Cacophony is a bit stronger because of its kicker cost. Especially when you have several opponents it can be very strong. As an instant we have Archive Trap.It's always funny when you meet an opponent who doesn't know the card or the deck, wants to pick a land with a fetchland turn 1 (e.g. Windswept Heath) and has to discard 13 cards. And that for 0 mana :) With a second copy of the card or Surgical extraction, some games can already be decided in the first turn. Last but not least, there is Mesmeric Orb, which slowly but surely mills every library. Since the opponent's library will be empty faster than ours, it doesn't bother us that we also have to mill a few cards.

Lands:

Our lands are a very important part of our strategy. So Hedron Crab and Ruin Crab can only reach their full potential when many lands enter the battlefield. How do we do that? With fetchlands! Polluted Delta, Prismatic Vista and Field of Ruin, which also interacts excellently with Archive Trap, ensure that we get a lot of trigger and thus many cards are milled. Oboro, Palace in the Clouds is a guarantee that more lands will enter the field later on.

Card draw:

This is certainly one of the weak points of the deck. For card drawing we only have one card, but it is outstanding. Visions of Beyond draws 3 cards for 1 mana. The legal version of Ancestral Recall which is just unfairly good after a certain point :)

Sideboard

The sideboard offers several answers to different decks as well as further copies of already existing cards in the deck. Bloodchief's Thirst is another removal spell that can also deal with planeswalkers. Damnation is the perfect answer to many cheap creatures that we otherwise wouldn't get off the field. Dauthi Voidwalker is meant to counter control decks or big creatures and beat the opponent with his own weapons :) Nighthawk Scavenger is a super strong single card that gives us sovereignty in the air and also generates a lot of life.Tasha's Hideous Laughter is a very new card, but from my point of view it is the perfect answer to very cheap and fast decks. Especially when the most expensive card in the opponent's deck only costs 3 mana, you can easily mill 10+ cards or even more.