After significant testing, here's a version that does ok. Delver at the moment is fundamentally a budget deck in standard. You are sacrificing quality for cheap cards, and the fun of playing a Delver deck in standard after nearly a decade. I believe this to be the best version of the Dimir deck at the moment (barring some meta-specific choices with your interaction). I'll explain why below, including a short review of the major cards this deck uses as well as notable exclusions. Dimir is not necessarily the best version of the Delver deck. There's a strong argument for Mono-Blue snow highlighting Ascendant Spirit and Demilich, and personally I think that people have been sleeping on Simic Delver, which could shake out as the best version of the archetype in current standard yet. I am not counting Izzet Delver in this conversation because, let's be real, that's a Goldspan Dragon deck and would be better off cutting the Delvers. The fact that it's a contender for the best delver deck is a testament to the fact that Delver is not going to be the terror it used to be with its current support.
Strategy
Like the Delver decks of old, this is fundamentally a tempo deck. The idea is to land a threat as early as possible and keep it alive while preventing your opponent from developing. This is the real advantage of Blue/Black delver, as your access to kill spells lets you prevent your opponents from building. One challenge with this deck is mulliganing correctly. This isn't a combo deck, and you need enough cards to keep from running out of gas, so you don't want to mulligan aggressively for the perfect hand. However, you absolutely need early threats, and you shouldn't be shy about dropping cards to ensure you get them. My rule of thumb (that I often contextually break) is that I need one of the following in order to keep a hand:
1) Turn 1 Delver
2) Turn 2 Suspicious Stowaway
3) Turn 2 Delver with support (Malakir Rebirth or Fading Hope most likely, though Village Rites can be good too)
I sometimes find myself keeping a hand with only a single land because it satisfies the Turn 1 Delver requirement. This is risky, but less so if you have consider in hand as well.
Another challenge is when to play your creatures. When you don't know what you're up against yet, the answer is usually to jam until shown that that's a bad route. If you're up against a deck with a lot of removal it can be beneficial to wait until you have an extra land or two to support your creature (with Malakir Rebirth, Fading Hope, Village Rites, or a kill spell if you're worried about fight spells). You're running a low number of threats for a deck that relies on creatures for damage, so you have to commit to ensuring that at least one of them sticks. In a lot of matchups, I think of Sedgemoor Witch and Poppet Stitcher as 4 drops because I NEED to get some value out of them before they get bolted.
Card Rundown
Agadeem's Awakening: I was not initially sold on the inclusion of this card, but I have seen the light. Agadeem's Awakening has several advantages. The first is simply that it is both a sorcery and potentially a fast land if you need it, triggering Delver without slowing you down. The second is that, if a game runs a little long, it is often exactly what you need to push your damage a over the edge. It also goes nicely with my choice to include Suspicious Stowaway (another controversial call), as Agadeem on 3 gives us three creatures back more often than not, and Agadeem on 2 is a viable play with a Delver and Stowaway in grave.
Bloodchief's Thirst, Flunk, Infernal Grasp, Power Word Kill, Ray of Enfeeblement, Soul Shatter: Your mileage will vary. tune your kill spells to what you're running into. This distribution in main and side has been playing nice enough for me, but because of the situational nature of the black kill in the current cycle this is the most likely thing to shift as the meta does. I would recommend running this number of kill spells in the main and side though. When sideboarding, this works nicely because vs angels your two copies of power word kill can come out for Ray of Enfeeblement. Vs. Dragons they come out for Soul Shatter.
Consider: This is an OK cantrip here (I actually think it's a pretty neat cantrip overall, but in this deck it's just ok). We don't really capitalize on what we pitch to grave outside of potentially Agadeem's Awakening, and it doesn't help to set up Delver. It does go nicely with Witch and Stitcher of course, but the reality is that it's here because we sorely need cantrips and this does the job alright. There's a decent chance it leaves the deck with future sets.
Delver of Secrets: What is there to say about this card that has not already been said? It's a great card, currently surrounded by very poor support. WoTC did that intentionally because of the waves Delver made when it first came out, I would bet money. I like that decision. Brewing with Delver is a lot more interesting when it isn't the most broken thing on the planet. Strategy-wise, your goal is to play this card and flip it as early as possible, but we don't have the best tools to do that with so the deck NEEDS to have strong plans B and C.
Fading Hope: The one true tool this deck runs for flipping Delver. Fading Hope is great. Use it to kill tokens, slow down opposing threats, set up Delver, save a creature, trigger Witch and Stitcher, dig for a threat when you're out of gas. It's never your most powerful card, but you're almost always happy to see it at any stage in the game.
Jwari Disruption: This card can have huge value early game, and is pretty underwhelming after that. I've occasionally had it win me games, but you often want to just play it as a land. Probably the weakest of the dual faced lands.
Malakir Rebirth: This card is great for keeping your creatures alive, and can be a land in a pinch when you're thinking about whether or not to keep a hand.
Poppet Stitcher: You'll notice I'm running three of these, which runs counter to conventional wisdom. Delver decks are supposed to run 16 threats. I think with our lack of ability to support flipping Delver with spells, and the fact that we have to push our curve higher than delver decks used to be we should be rethinking this logic. Poppet Stitcher is a great aggressive play, but with the amount of removal currently in standard I would almost always rather have Sedgemoor who can at least get three damage in when targeted, and serves as a credible threat herself with menace even without the tokens. Stitcher can be an incredibly explosive threat when he flips, winning all on his own sometimes, but is the less reliable three drop in the deck.
Sedgemoor Witch: Remember to let her ward resolve before you play your answers, that three damage can be clutch. Sedgemoor is annoying, and plays into one of this deck's greatest strengths: the unavoidable damage. If you have Witch and Stitcher in hand the answer is almost always to play Witch first to set up a Stitcher who will immediately flip the next turn, unless you need to be blocking 2 power creatures.
Suspicious Stowaway: Stowaway is a controversial inclusion, with some decks opting to run just three creatures. Personally, I think Stowaway is quite strong, giving you another creature that can get in early unavoidable damage (or at least pull out kill spells), as well as card selection or even advantage if he sticks around. Plus, some opponents will jam spells in order to prevent his transformation allowing you to punish them as they run low on cards.
Village Rites: Great with a Witch or Stitcher as the token will replace itself and you get cards. Better with multiple as you get more tokens. Ok as a response to kill to give yourself a bit of a reload.
Hive of the Eye Tyrant: Don't forget about your man land! This is extremely helpful for pushing your damage over the edge after you've run out of gas.
Disdainful Stroke: Good against control, good against dragons. Sometimes underwhelming against ramp, but still worth siding in.
Duress: I'm not convinced yet that the better inclusion isn't check for traps, as we don't usually play this turn 1. More testing needed here.
Negate, Test of Talents: If a deck runs few to no creatures you want to be able to stop their spells, simple enough to know when to swap.
Notable Exclusions
Siphon Insight: I think this is a trap in this deck. Quite often, the "card advantage" this gives doesn't play nice with your gameplan. It should stay in control where it belongs.
Otherworldly Gaze: This card is great for setting up Delver, OK card selection, but for the most part just kind of bad. I'm open to the possibility that it will turn out to be a correct inclusion, but I doubt it.
Ebondeath, Dracolich: Here's an interesting option. Adds another layer to what you can do with Agadeem, can be a fantastic surprise beater coming in on an endstep, and helps the deck to keep from running out of gas. Don't run more than 2, because this card is dead in your core gameplan, but it might have enough "Plan B" potential to be worth finding a slot. I've tried him out and am happier without him, but he wasn't so bad that I feel he's not worth consideration.
Iymrith, Desert Doom: Don't, Ebondeath is far better in this deck.
Ascendant Spirit, Blood on the Snow: I think there's something to be said for trying a more controlling version of this deck that runs snow lands and something like this, but I think that line will ultimately fail. That deck is going to struggle hard with an identity problem between tempo and control, and I don't see it ever finding a satisfying answer.
The Meathook Massacre: I tried this one, I wanted it to work, and sometimes it did. Meathook such a versatile card in a deck like this. You can drop it on turn 2 to gain incremental value and damage throughout the game. You can drop it turn 4 to reset the board state if your opponent is ahead. You can drop it late game to slaughter your own tokens and push your damage over the edge. I had all of these things happen and create value in testing. Sadly, there were also a lot of games when I would groan at seeing it. Missed Delver triggers, not enough mana to wipe my opponent's board, etc... At the end of the day, I couldn't justify including it, but it's a cool card with surprising potential for our strategy despite the obvious elements of anti-synergy.
