Case of the Burning Masks

When this Case enters, it deals 3 damage to target creature an opponent controls.
To solve — Three or more sources you controlled dealt damage this turn. (If unsolved, solve at the beginning of your end step.)
Solved — Sacrifice this Case: Exile the top three cards of your library. Choose one of them. You may play that card this turn.

Red Herring

Haste
Red Herring attacks each combat if able.
{2}, Sacrifice Red Herring: Draw a card.

Meddling Youths

Haste
Whenever you attack with three or more creatures, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Gearbane Orangutan

Reach
When Gearbane Orangutan enters, choose one —
• Destroy up to one target artifact.
• Sacrifice an artifact. If you do, put two +1/+1 counters on Gearbane Orangutan.

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.")

Makeshift Binding

When Makeshift Binding enters, exile target creature an opponent controls until Makeshift Binding leaves the battlefield. You gain 2 life.

Galvanize

Galvanize deals 3 damage to target creature. If you've drawn two or more cards this turn, Galvanize deals 5 damage to that creature instead.

Mountain

Torch the Witness

Torch the Witness deals twice X damage to target creature. If excess damage was dealt to that creature this way, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Lightning Helix

Lightning Helix deals 3 damage to any target and you gain 3 life.

Warleader's Call

Creatures you control get +1/+1.
Whenever a creature you control enters, Warleader's Call deals 1 damage to each opponent.

Novice Inspector

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

Marketwatch Phantom

Whenever another creature you control with power 2 or less enters, Marketwatch Phantom gains flying until end of turn.

Inside Source

When Inside Source enters, create a 2/2 white and blue Detective creature token.
{3}, {T}: Target Detective you control gets +2/+0 and gains vigilance until end of turn. Activate only as a sorcery.

Gadget Technician

When Gadget Technician enters or is turned face up, create a 1/1 colorless Thopter artifact creature token with flying.
Disguise {U/R}{U/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.)

Person of Interest

When Person of Interest enters, suspect it. Create a 2/2 white and blue Detective creature token. (A suspected creature has menace and can't block.)

Karlov Watchdog

Vigilance
Permanents your opponents control can't be turned face up during your turn.
Whenever you attack with three or more creatures, creatures you control get +1/+1 until end of turn.

Aurelia, the Law Above

Flying, vigilance, haste
Whenever a player attacks with three or more creatures, you draw a card.
Whenever a player attacks with five or more creatures, Aurelia, the Law Above deals 3 damage to each of your opponents and you gain 3 life.

Plains

On the Job

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

Reckless Detective

Whenever Reckless Detective attacks, you may sacrifice an artifact or discard a card. If you do, draw a card and Reckless Detective gets +2/+0 until end of turn.

Dog Walker

Vigilance
Disguise {R/W}{R/W} (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 Dog Walker is turned face up, create two tapped 1/1 white Dog creature tokens.

Shock

Pyrotechnic Performer

Disguise {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.)
Whenever Pyrotechnic Performer or another creature you control is turned face up, that creature deals damage equal to its power to each opponent.