Knife

During your turn, equipped creature gets +1/+0 and has first strike.
{2}, Sacrifice Knife: Draw a card.
Equip {2}

Red Herring

{1}{U}: Exchange Red Herring from your hand with a permanent you control on the battlefield or a spell you control on the stack. If that permanent or spell was the target of a spell or ability, change that target to Red Herring.

Curious Inquiry

Enchant creature
Enchanted creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, investigate." (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Out Cold

This spell can't be countered. (This includes by the ward ability.)
Tap up to two target creatures and put a stun counter on each of them. Investigate. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Mistway Spy

Flying
Disguise {1}{U} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)
When Mistway Spy is turned face up, until end of turn, whenever a creature you control deals combat damage to a player, investigate.

Lamplight Phoenix

Flying
When Lamplight Phoenix dies, you may exile it and collect evidence 4. If you do, return Lamplight Phoenix to the battlefield tapped. (To collect evidence 4, exile cards with total mana value 4 or greater from your graveyard.)

Intrude on the Mind

Reveal the top five cards of your library and separate them into two piles. An opponent chooses one of those piles. Put that pile into your hand and the other into your graveyard. Create a 0/0 colorless Thopter artifact creature token with flying, then put a +1/+1 counter on it for each card put into your graveyard this way.

Crimestopper Sprite

As an additional cost to cast this spell, you may collect evidence 6. (Exile cards with total mana value 6 or greater from your graveyard.)
Flying
When Crimestopper Sprite enters, tap target creature. If evidence was collected, put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Projektor Inspector

Whenever Projektor Inspector or another Detective you control enters and whenever a Detective you control is turned face up, you may draw a card. If you do, discard a card.

Krenko, Baron of Tin Street

Haste
{T}, Sacrifice an artifact: Put a +1/+1 counter on each Goblin you control.
Whenever an artifact is put into a graveyard from the battlefield, you may pay {R}. If you do, create a 1/1 red Goblin creature token. It gains haste until end of turn.

Candlestick

Equipped creature gets +1/+1 and has "Whenever this creature attacks, surveil 2." (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
{2}, Sacrifice Candlestick: Draw a card.
Equip {2}

Furtive Courier

Furtive Courier can't be blocked as long as you've sacrificed an artifact this turn.
Whenever Furtive Courier attacks, draw a card, then discard 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.

The Chase Is On

Target creature gets +3/+0 and gains first strike until end of turn. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Mountain

Case of the Filched Falcon

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

Cold Case Cracker

Flying
When Cold Case Cracker dies, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Thundering Falls

({T}: Add {U} or {R}.)
Thundering Falls enters tapped.
When Thundering Falls enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Concealed Weapon

Equipped creature gets +3/+0.
Disguise {2}{R} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)
When Concealed Weapon is turned face up, attach it to target creature you control.
Equip {1}{R}

Reasonable Doubt

Counter target spell unless its controller pays {2}.
Suspect up to one target creature. (A suspected creature has menace and can't block.)

Gravestone Strider

{1}: Add one mana of any color. Activate only once each turn.
{2}, Exile Gravestone Strider from your graveyard: Exile target card from a graveyard.