Surveil is a strong keyword on its own, and doubly so when it buffs our main attackers. This deck is a fairly cheap way to take advantage of Dimir's new keyword. While not strong in the early game, this deck packs a punch after we surveil a few times. In particular, Dimir Spybug is very evasive sporting the flying+menace combo, meaning that it should be able to do serious damage reliably unless victim to targeted removal. Thoughtbound Phantasm is our other main bruiser, acting as a wall until we can hit our stride.
Watchful Eyes
Nightveil Sprite is our most reliable, recurring source of surveil triggers. It is worth noting that the surveil occurs before combat damage is dealt, meaning concurrent swings with the aforementioned bruisers allows you to swing earlier. Discovery / Dispersal is our next most reliable surveil trigger. Surveiling 2 and replacing itself is very solid. Dispersal can be used for removal later, but is not the primary reason for this cards inclusion. Notion Rain, while giving better card advantage, can be difficult to use against more aggressive decks, and may become a dead card in close games where you can't lose life.
Controlling the Field
Dimir has no shortage of controlling cards, but with limited space finding the right ones is important. With cards that take time to buff up, the cheap safety that Dive Down provides takes high priority. Unless our opponent is running little to no removal, this card is crucial. Even against those decks, it allows us to turn trades into favorable exchanges. Thought Erasure can be less consistent, but allows for more ways of tampering with an opponent's gameplan. Taking away critical spells and creatures before they hit the board and getting a surveil trigger is nothing to scoff at. Alternatives were considered here, and make appearances as sideboard cards as they tend to be less flexible in execution.
Supporting Surveillence
Enhanced Surveillance gives us enormous control over our next cards. Disinformation Campaign gives premier card advantage, but finding the mana to repeatedly cast it can be difficult unless the game goes long. Having multiples of these would be more problematic if surveil didn't allow us to toss the duplicates after the first hits the board, so running four copies of each can be considered. Creeping Chill has amazing synergy if you can toss it, and this deck surveils consistently enough that you will typically be able to do so. Having it in hand is sub-optimal, but we can still find time to cast it later. The risk of a weak draw is worth the reward of a free 3 drain with how consistently we can surveil--the same cannot be said for Narcomeba.
One of a Kind
The elephant in the room for surveil is obviously Doom Whisperer--a powerful card in its own right, and capable of hitting the field and boosting our bruisers in the same breath at the cost of any spare life we have. There's obviously a risk that comes with that, especially against burn heavy decks, but on demand surveil is ridiculous, never mind having a 6/6 flying trample for five. Its inarguably a good card in standard, but that power comes with a price. Literally. The only reason I run only one of this card is the $20+ price tag, and I'd probably not be running this one if I didn't happen to open it. If you have the budget to include more, they will certainly add some power and consistency, especially since this card will eat counters and removal real quick.
Lazav, the Multifarious is exceptionally efficient in this deck. A 1/3 for 2 that surveils when it enters isn't bad, and being able to copy any tossed or removed cards of ours can help with consistency--especially with only one Doom Whisperer. Copying Dimir Spybug is handy too, or even a Nightveil Sprite in a pinch. Again, running more might help round out the consistency, but in this case we run the risk of giving up the very things that Lazav helps us patch up.
A Side Note
Unmoored Ego is a card I really like, but unfortunately doesn't quite have the right meta to truly shine. Being able to obliterate combo pieces for 3 is very nice in standard--if there were any major combo decks running around. Still, it has its place as a preemptive removal option against certain cards. This is enough to earn a sideboard slot for me.
Sinister Sabotage is a card I had mainboarded for a while, but often felt hindered by. Unlike many blue decks, this deck doesn't like leaving mana hanging open. Holding mana for counters slows us down enormously, and often doesn't find a target. Works well against spell heavy decks all the same however, especially ones that run towards late game where we have the mana to spare. This card can turn critical moments, but is too detrimental in aggressive matchups to mainboard in my opinion.
Unexplained Disappearance is the opposite of our last card. It provides a good way to early stall and keep +1/+1 tokens from piling up, while also boosting our bruisers. Cheaper than our counterspell too, it is much easier to run and worth considering on the mainboard. You can also save a creature in theory with this, but since we want to pile tokens on them this isn't ideal.
Mephitic Vapors is my most tenuous sideboard option. In theory, this can clear token spamming decks, but this is exceptionally niche. Using it against Boros is wishful thinking, but will never really work out. Also worth noting is that Dimir Spybug will die before the surveil trigger can save it, so use with caution. A potential improvement here would be Ritual of Soot to slow down Boros decks, though unfortunately that will clear out most of our board as well.
Price of Fame, for those creatures we can't leave alive on the board. 4 CMC to destroy a creature and surveil isn't bad by any means, making it the go to kill spell for this deck, but the value on this when targeting legendary creatures is enormous. A strong case can be made for mainboarding this, but ultimately I've decided not to for my use. Other removal spells to be considered here are Necrotic Wound which often can remove for one, but relies on our creatures dying to scale unless we can be sure we won't need the extra bodies on the field, in which case surveil can fuel this nicely. Vraska's Contempt also has a niche in allowing us to hit planeswalkers as well--consider it if many show up in your sphere.
