While the spoilers for Murders at Karlov Manor continue to trickle in, there is a clearly defining characteristic that many of the cards share:
Clue


Much Hype, Some Substance

Just a few years ago
Viridian Revel






Of course, Revel works with any artifacts going to the graveyard, not just tokens. While the price and the hype on this card has cooled a bit, it’s still a very playable card, and in light of another set with a heavy artifact sacrifice theme, it can only perform even better. If you have slotted out Viridian Revel for something else, consider giving it another try. You may be pleasantly surprised but how solid it is.
Smothering Tithe

An Old School Green Option

First, this stops non-creature artifacts cold turning off all their abilities. Next, it turns them into creatures. Finally, it has a unique effect that persists until end of turn, so even if it’s removed, it effectively is not for that turn, at least.
Titania’s Song



Now, Titania’s Song could be an advantage too. Maybe you want something to trigger Investigate, making a bunch of clues, but you want them to go to the graveyard for
Marionette Master

Whenever an artifact you control is put into a graveyard from the battlefield, target opponent loses life equal to this creature's power.
or
Disciple of the Vault

Landfall

Green has plenty of ways to fight clues including
Collector Ouphe


Whenever you sacrifice a Clue, put a +1/+1 counter on this creature.
gives you a very easy way for green to generate an excessive number of clues very quickly. As a side-effect to sacrificing clues, your Tracker is going to grow to epic proportions. Note that you don’t have to activate the clues, or pay mana. Merely sacrificing the clues will permanently boost the Tracker. What better way, in green, than the innocuous
Glimmer Bairn

Big Mana Synergy

Just imagine if instead of Investigate making a clue, you made a
Mox Emerald


If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.
at the ready.
Potential Synergy in Black

First, we have not seen much out of black for Murders at Karlov Manor. Second, the color is historically weak to both artifacts and enchantments. Even so Braids, Arisen Nightmare lets you turn extra clue tokens into edict effects than can also deal damage and draw you cards. Clearly there will be excess clue tokens aplenty, so Braids turns your slow draw power into faster draw power that also can set your opponents back. It’s a bit speculative, but the set definitely will boost Braids power a little.
Black does, however, get to include Havengul Laboratory as it has black color identity. A relatively free reanimation effect that takes up no deck space makes this card an auto include in every black deck with a clue theme.
Red Always has Interesting Answers

Is your opponent trying to maintain a critical mass of clues to go off? Meet Sardian Avenger who can attack into pretty much anything for value. Keep this idea in mind because it’s all about diplomacy.
You see, clues tend to stick around a relatively long time, they offer a slow advantage, but you do not have to attack the player massing up clues to get the bonus. Therefore, they are helping you take down the other two players. Meanwhile, when they crack their clues, they are still taking damage for it. For only two mana, the Avenger has the potential to deal gobs of damage in multiplayer. Considering you’re in red, you have easy access to double-strike and double damage effects to one shot players. Let that player make
Treasure


Doctor Who is all About Clues

There are a lot of potential combinations of Commanders from the MTG Doctor Who set. While Jenny Flynt and Madame Vastra could be decent Commander for this style of deck, I think they would be better off as a tutoring pair in the 98. Meanwhile, Nyssa of Traken is the real Commander of the deck with The Fugitive Doctor as the backup plan. You should be able to easily make three to five clues before Nyssa takes her first swing and refills your hand. Even if you draw too much, she removes your hand size limit!
If things don’t work out, your Doctor can come in, generate a clue and then start using Flashback to replay all your spells. Once you generate even more clues, Nyssa will get back to work drawing a gazillion cards. Both green and blue have tons of excellent support for this type of game plan. Blue even ramps hard with Five Hundred Year Diary. Red will have excellent spells that you want to flash back and can also make a lot of treasure which will have synergy with the rest of the deck and other auto includes.
Then Again, so is Stranger Things

Mardu is allowed to get in on the
Clue



Whenever an artifact you control is put into a graveyard from the battlefield, target opponent loses life equal to this creature's power.
as mentioned briefly above but you can easily go a different way. Note how Wernog, Rider’s Chaplain gives your opponents clues which boosts up Sardian Avenger. With a bit of help from Murders at Karlov Manor, this could be the start of some very interesting looking decks.
Speaking of White

It appears that Thorough Investigation has already spiked in price and for good reason as it’s the best investigate card in white with the highest
Clue

The dungeon mechanic, overall, is relatively slow but it does provide advantage. If you can turbo your way through an entire dungeon all at once, at instant speed, however, you can have a surprising impact at any stage of a game. While Search the Premises deserves a mention, it relies too much on your opponents to gain value. Thorough Investigation gives you explosive potential as long as you have a sacrifice outlet for your clues and is a card with strong potential. Once we see more of Murders at Karlov Manor you may end up wanting it.
Blue has too much…

First, let’s talk about some multicolored cards that include blue.
Lonis, Cryptozoologist

{T}, Sacrifice X Clues: Target opponent reveals the top X cards of their library. You may put a nonland permanent card with mana value X or less from among them onto the battlefield under your control. That player puts the rest on the bottom of their library in a random order.
is likely an auto-include in any clue heavy simic deck and a combo commander. Time Sieve loves to eat extra clues and it’s quite possible to make enough each turn to go infinite. Surely Eloise, Nephalia Sleuth, Inquisitor Eisenhorn, and Inquisitor Greyfax will all see play. But what are the absolute standout mono-blue cards?
It’s a toss up between Trail of Evidence and
Ethereal Investigator

When this creature enters, investigate X times, where X is the number of opponents you have. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you draw your second card each turn, create a 1/1 white Spirit creature token with flying.
. The Investigator has tremendous upside when it’s generating three clues every time it enters the battlefield. This card wants to be bounced, blinked, flickered and reanimated. On top of making a pile of clues, it also is quite easy to generate some additional 1/1 spirit tokens for even more value. Meanwhile, Trail of Evidence just generates a clue for every instant or sorcery you cast, so if you’re a spell heavy deck, it will do a large amount of work. Where there is smoke, there is fire, and many decks will simply play both.
There can be only one best Artifact

Let’s face it, generating a single
Clue


Clues and Investigation
There’s not much to go on right now in regards to just how Murders at Karlov Manor will impact Magic’s various formats. Even with only these two mechanics in play, there are a lot of cards ready to see more play. Based on pure speculation, there should be all manner of card archetypes that will soon interact with
Clue
