The Third Doctor

Trample
The Third Doctor gets +1/+1 for each noncreature token you control.
When The Third Doctor enters, create your choice of a Clue token, a Food token, or a Treasure token.

Organic Extinction

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Destroy all nonartifact creatures.

Serene Sleuth

When Serene Sleuth enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
At the beginning of combat on your turn, investigate for each goaded creature you control. Then each creature you control is no longer goaded.

Windswept Heath

{T}, Pay 1 life, Sacrifice Windswept Heath: Search your library for a Forest or Plains card, put it onto the battlefield, then shuffle.

Merchant of Truth

Flying
Whenever a nontoken creature you control dies, investigate.
Clues you control have exalted. (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn for each instance of exalted among permanents you control.)

Morska, Undersea Sleuth

You have no maximum hand size.
At the beginning of your upkeep, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you draw your second card each turn, put two +1/+1 counters on Morska, Undersea Sleuth.

Knowledge Is Power

Creatures you control get +X/+X, where X is the number of cards you've drawn this turn.

Flooded Strand

{T}, Pay 1 life, Sacrifice Flooded Strand: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Senator Peacock

Artifacts you control are Clues in addition to their other types and have "{2}, Sacrifice this artifact: Draw a card."
Whenever you sacrifice a Clue, target creature can't be blocked this turn.

Armed with Proof

When Armed with Proof enters, investigate twice. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Clues you control are Equipment in addition to their other types and have "Equipped creature gets +2/+0" and equip {2}.

Basalt Monolith

Basalt Monolith doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{3}: Untap Basalt Monolith.

Glacial Fortress

Glacial Fortress enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Lonis, Genetics Expert

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Whenever one or more +1/+1 counters are put on Lonis, investigate that many times.
Whenever you sacrifice a Clue, put a +1/+1 counter on another target creature you control.

Sally Sparrow

You may cast creature spells as though they had flash.
Whenever one or more other creatures you control leave the battlefield, investigate. This ability triggers only once each turn. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Simic Signet

Sharp-Eyed Rookie

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

Kitchen

Kitchen enters tapped.
{T}: Add {G} or {U}.
{4}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Overgrown Farmland

Overgrown Farmland enters tapped unless you control two or more other lands.
{T}: Add {G} or {W}.

Ezrim, Agency Chief

Flying
When Ezrim, Agency Chief enters, investigate twice. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
{1}, Sacrifice an artifact: Ezrim gains your choice of vigilance, lifelink, or hexproof until end of turn.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Bennie Bracks, Zoologist

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
At the beginning of each end step, if you created a token this turn, draw a card.

Deduce

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

Root Out

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

Forest

Lavinia, Foil to Conspiracy

Vigilance
Whenever you cast your second spell each turn, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
{T}: Add {C}{C}. Activate only during an opponent's turn.

Investigator's Journal

Investigator's Journal 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 Investigator's Journal: Draw a card.
{2}, Sacrifice Investigator's Journal: Draw a card.

Sarah Jane Smith

Whenever you cast a historic spell, investigate. This ability triggers only once each turn. (Artifacts, legendaries, and Sagas are historic. To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Doctor's companion (You can have two commanders if the other is the Doctor.)

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Temple Garden

({T}: Add {G} or {W}.)
As Temple Garden enters, you may pay 2 life. If you don't, it enters tapped.

Ethereal Investigator

Flying
When Ethereal Investigator 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 artifact: Draw a card.")
Whenever you draw your second card each turn, create a 1/1 white Spirit creature token with flying.

Sea of Clouds

Sea of Clouds enters tapped unless you have two or more opponents.
{T}: Add {W} or {U}.

Fleeting Memories

When Fleeting Memories enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice a Clue, target player mills three cards.

Follow the Bodies

Gravestorm (When you cast this spell, copy it for each permanent put into a graveyard from the battlefield this turn.)
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Hinterland Harbor

Hinterland Harbor enters tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.

Spara's Headquarters

({T}: Add {G}, {W}, or {U}.)
Spara's Headquarters enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

No Witnesses

Each player who controls the most creatures investigates. Then destroy all creatures. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Plains

Junk Winder

Affinity for tokens (This spell costs {1} less to cast for each token you control.)
Whenever a token you control enters, tap target nonland permanent an opponent controls. It doesn't untap during its controller's next untap step.

Tangletrove Kelp

Ward {2}
At the beginning of each combat, other Clues you control become 6/6 Plant creatures in addition to their other types until end of turn.
{2}, Sacrifice Tangletrove Kelp: Draw a card.

Adrix and Nev, Twincasters

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
If one or more tokens would be created under your control, twice that many of those tokens are created instead.

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.

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 artifact: Draw a card.")

Sol Ring

Selesnya Signet

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 artifact: Draw a card.")

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Osgood, Operation Double

When you cast this spell, create a token that's a copy of it, except it isn't legendary.
{T}: Add {C}. Spend this mana only to cast an artifact spell or activate an ability of an artifact.
Paradox — Whenever you cast a spell from anywhere other than your hand, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Agent's Toolkit

Agent's Toolkit enters with a +1/+1 counter, a flying counter, a deathtouch counter, and a shield counter on it. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)
Whenever a creature you control enters, you may move a counter from Agent's Toolkit onto that creature.
{2}, Sacrifice Agent's Toolkit: Draw a card.

Fateful Absence

Destroy target creature or planeswalker. Its controller investigates. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Prairie Stream

({T}: Add {W} or {U}.)
Prairie Stream enters tapped unless you control two or more basic lands.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.

Tamiyo's Journal

At the beginning of your upkeep, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
{T}, Sacrifice three Clues: Search your library for a card, put that card into your hand, then shuffle.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

On the Trail

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

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.)

Disorder in the Court

Exile X target creatures, then investigate X times. Return the exiled cards to the battlefield tapped under their owners' control at the beginning of the next end step. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Alquist Proft, Master Sleuth

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

Weirding Wood

Enchant land
When Weirding Wood enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Enchanted land has "{T}: Add two mana of any one color."

Idol of Oblivion

{T}: Draw a card. Activate only if you created a token this turn.
{8}, {T}, Sacrifice Idol of Oblivion: Create a 10/10 colorless Eldrazi creature token.

Lonis, Cryptozoologist

Whenever another nontoken creature you control enters, investigate.
{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.

Wilderness Reclamation

At the beginning of your end step, untap all lands you control.

Island

Wavesifter

Flying
When Wavesifter enters, investigate twice. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Evoke {G}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Arcane Signet

Tireless Tracker

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

Rejuvenating Springs

Rejuvenating Springs enters tapped unless you have two or more opponents.
{T}: Add {G} or {U}.

Conservatory

Conservatory enters tapped.
{T}: Add {G} or {W}.
{4}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Forensic Gadgeteer

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

Breeding Pool

({T}: Add {G} or {U}.)
As Breeding Pool enters, you may pay 2 life. If you don't, it enters tapped.

Scene of the Crime

Scene of the Crime enters tapped.
{T}: Add {C}.
{T}, Tap an untapped creature you control: Add one mana of any color.
{2}, Sacrifice Scene of the Crime: Draw a card.

Five Hundred Year Diary

Five Hundred Year Diary enters tapped.
{T}: Add {U} for each Clue you control.
{2}, Sacrifice Five Hundred Year Diary: Draw a card.

Erdwal Illuminator

Flying
Whenever you investigate for the first time each turn, investigate an additional time.

Study

Study enters tapped.
{T}: Add {W} or {U}.
{4}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Misty Rainforest

{T}, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

Ongoing Investigation

Whenever one or more creatures you control deal combat damage to a player, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
{1}{G}, Exile a creature card from your graveyard: Investigate. You gain 2 life.

Trail of Evidence

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

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, Inquisitive Prodigy attacks, destroy up to one target artifact. If you controlled that permanent, draw a card.

Kellan, Inquisitive Prodigy // Tail the Suspect

Deserted Beach

Deserted Beach enters tapped unless you control two or more other lands.
{T}: Add {W} or {U}.

Wojek Investigator

Flying, vigilance
At the beginning of your upkeep, investigate once for each opponent who has more cards in hand than you. (To investigate, create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Hallowed Fountain

({T}: Add {W} or {U}.)
As Hallowed Fountain enters, you may pay 2 life. If you don't, it enters tapped.

Bountiful Promenade

Bountiful Promenade enters tapped unless you have two or more opponents.
{T}: Add {G} or {W}.

Hold for Questioning

Enchant creature or planeswalker
When Hold for Questioning enters, tap enchanted permanent and investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Enchanted permanent doesn't untap during its controller's untap step and its activated abilities can't be activated.

Magnifying Glass

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

Sunpetal Grove

Sunpetal Grove enters tapped unless you control a Forest or a Plains.
{T}: Add {G} or {W}.

Dreamroot Cascade

Dreamroot Cascade enters tapped unless you control two or more other lands.
{T}: Add {G} or {U}.

Inspiring Statuary

Nonartifact spells you cast have improvise. (Your artifacts can help cast those spells. Each artifact you tap after you're done activating mana abilities pays for {1}.)

Briarbridge Patrol

Whenever Briarbridge Patrol deals damage to one or more creatures, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: 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.

Tezzeret, Betrayer of Flesh

The first activated ability of an artifact you activate each turn costs {2} less to activate.
+1: Draw two cards. Then discard two cards unless you discard an artifact card.
−2: Target artifact becomes an artifact creature. If it isn't a Vehicle, it has base power and toughness 4/4.
−6: You get an emblem with "Whenever an artifact you control becomes tapped, draw a card."

Azorius Signet

Academy Manufactor

If you would create a Clue, Food, or Treasure token, instead create one of each.

Martha Jones

Woman Who Walked the Earth — When Martha Jones enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")
Whenever you sacrifice a Clue, Martha Jones and up to one other target creature can't be blocked this turn.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Ulvenwald Mysteries

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