Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Search the Premises

Whenever a creature attacks you or a planeswalker you control, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Memory

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Each player shuffles their hand and graveyard into their library, then draws seven cards.

Commit

Put target spell or nonland permanent into its owner's library second from the top.

Commit // Memory

Ethereal Investigator

Flying
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.

Explore

You may play an additional land this turn.
Draw a card.

Alquist Proft, Master Sleuth

Vigilance
When Alquist Proft enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
{X}{W}{U}{U}, {T}, Sacrifice a Clue: You draw X cards and gain X life.

Forensic Gadgeteer

Whenever you cast an artifact spell, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Activated abilities of artifacts you control cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.

No More Lies

Counter target spell unless its controller pays {3}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Magnifying Glass

{T}: Add {C}.
{4}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Duelist of the Mind

Flying, vigilance
Duelist of the Mind's power is equal to the number of cards you've drawn this turn.
Whenever you commit a crime, you may draw a card. If you do, discard a card. This ability triggers only once each turn.

Press for Answers

Tap target creature. It doesn't untap during its controller's next untap step.
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Tireless Tracker

Landfall — Whenever a land you control enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you sacrifice a Clue, put a +1/+1 counter on this creature.

Private Eye

Other Detectives you control get +1/+1.
Whenever you draw your second card each turn, target Detective can't be blocked this turn.

Tail the Suspect

Investigate. You may play an additional land this turn. (Then exile this card. You may cast the creature later from exile.)

Kellan, Inquisitive Prodigy

Flying, vigilance
Whenever Kellan attacks, destroy up to one target artifact. If you controlled that permanent, draw a card.

Kellan, Inquisitive Prodigy // Tail the Suspect

Bearer of Overwhelming Truths

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever this creature deals combat damage to a player, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Daring Sleuth

When you sacrifice a Clue, transform this creature.

Daring Sleuth // Bearer of Overwhelming Truths

Case of the Pilfered Proof

Whenever a Detective you control enters or is turned face up, put a +1/+1 counter on it.
To solve — You control three or more Detectives. (If unsolved, solve at the beginning of your end step.)
Solved — If one or more tokens would be created under your control, those tokens plus a Clue token are created instead. (It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Detainment Spell

Enchant creature
Enchanted creature's activated abilities can't be activated.
{1}{W}: Attach this Aura to target creature.

Reverse Engineer

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Draw three cards.

Selfless Savior

Sacrifice this creature: Another target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

They Went This Way

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Freestrider Lookout

Reach
Whenever you commit a crime, look at the top five cards of your library. You may put a land card from among them onto the battlefield tapped. Put the rest on the bottom of your library in a random order. This ability triggers only once each turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)

Trail of Evidence

Whenever you cast an instant or sorcery spell, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Dig Through Time

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Look at the top seven cards of your library. Put two of them into your hand and the rest on the bottom of your library in any order.

Masked Vandal

Changeling (This card is every creature type.)
When this creature enters, you may exile a creature card from your graveyard. If you do, exile target artifact or enchantment an opponent controls.

Novice Inspector

When this creature enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Gone Missing

Put target permanent on top of its owner's library.
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Bootleggers' Stash

Lands you control have "{T}: Create a Treasure token."

Officious Interrogation

This spell costs {W}{U} more to cast for each target beyond the first.
Choose any number of target players. Investigate X times, where X is the total number of creatures those players control.

Wary Watchdog

When this creature enters or dies, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Hold for Ransom

Enchant creature
Enchanted creature can't attack or block and has "{7}: Hold for Ransom's controller sacrifices it and draws a card. Activate only as a sorcery."

Case of the Filched Falcon

When this Case enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
To solve — You control three or more artifacts. (If unsolved, solve at the beginning of your end step.)
Solved — {2}{U}, Sacrifice this Case: Put four +1/+1 counters on target noncreature artifact. It becomes a 0/0 Bird creature with flying in addition to its other types.

Suspicious Bookcase

Defender
{3}, {T}: Target creature can't be blocked this turn.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Sophia, Dogged Detective

When Sophia enters, create Tiny, a legendary 2/2 green Dog Detective creature token with trample.
{1}, Sacrifice an artifact token: Put a +1/+1 counter on each Dog you control.
Whenever a Dog you control deals combat damage to a player, create a Food token, then investigate.

Floodhound

{3}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Confirm Suspicions

Counter target spell.
Investigate three times. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Evacuation

Return all creatures to their owners' hands.

Case of the Gateway Express

When this Case enters, choose target creature you don't control. Each creature you control deals 1 damage to that creature.
To solve — Three or more creatures attacked this turn. (If unsolved, solve at the beginning of your end step.)
Solved — Creatures you control get +1/+0.

Disruption Protocol

As an additional cost to cast this spell, tap an untapped artifact you control or pay {1}.
Counter target spell.

Ulvenwald Mysteries

Whenever a nontoken creature you control dies, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you sacrifice a Clue, create a 1/1 white Human Soldier creature token.

Investigator's Journal

This artifact enters with a number of suspect counters on it equal to the greatest number of creatures a player controls.
{2}, {T}, Remove a suspect counter from this artifact: Draw a card.
{2}, Sacrifice this artifact: Draw a card.

Clifftop Lookout

Reach
When this creature enters, reveal cards from the top of your library until you reveal a land card. Put that card onto the battlefield tapped and the rest on the bottom of your library in a random order.

Nimble Brigand

This creature can't be blocked if you've committed a crime this turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)
Whenever this creature deals combat damage to a player, draw a card.

Sharp-Eyed Rookie

Vigilance
Whenever a creature you control enters, if its power is greater than this creature's power or its toughness is greater than this creature's toughness, put a +1/+1 counter on this creature and investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Supreme Verdict

This spell can't be countered.
Destroy all creatures.

Confront the Unknown

Investigate, then target creature gets +1/+1 until end of turn for each Clue you control. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Dispatch

Tap target creature.
Metalcraft — If you control three or more artifacts, exile that creature.

Universal Surveillance

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Draw X cards.

Oko, the Ringleader

At the beginning of combat on your turn, Oko becomes a copy of up to one target creature you control until end of turn, except he has hexproof.
+1: Draw two cards. If you've committed a crime this turn, discard a card. Otherwise, discard two cards.
−1: Create a 3/3 green Elk creature token.
−5: For each other nonland permanent you control, create a token that's a copy of that permanent.

Deduce

Draw a card. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Witness Protection

Enchant creature
Enchanted creature loses all abilities and is a green and white Citizen creature with base power and toughness 1/1 named Legitimate Businessperson. (It loses all other colors, card types, creature types, and names.)

In Too Deep

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Enchant creature, planeswalker, or Clue
Enchanted permanent is a colorless Clue artifact with "{2}, Sacrifice this artifact: Draw a card" and loses all other abilities. (It's no longer a creature or planeswalker.)

Hard Evidence

Create a 0/3 blue Crab creature token.
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Detective of the Month

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
As long as you have the city's blessing, Detectives you control can't be blocked.
Whenever you draw your second card each turn, create a 2/2 white and blue Detective creature token.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Briarbridge Patrol

Whenever this creature deals damage to one or more creatures, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
At the beginning of each end step, if you sacrificed three or more Clues this turn, you may put a creature card from your hand onto the battlefield.

Arrest

Enchant creature
Enchanted creature can't attack or block, and its activated abilities can't be activated.

On the Trail

Whenever you draw your second card each turn, you may put a land card from your hand onto the battlefield tapped.

Cathar's Companion

Whenever you cast a noncreature spell, this creature gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Hunter's Insight

Choose target creature you control. Whenever that creature deals combat damage to a player or planeswalker this turn, draw that many cards.

An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Root Out

Destroy target artifact or enchantment.
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Resolute Watchdog

Defender
{1}, Sacrifice this creature: Target creature you control gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Cast Out

Flash
When this enchantment enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield.
Cycling {W} ({W}, Discard this card: Draw a card.)