Blood Spatter Analysis

When this enchantment enters, it deals 3 damage to target creature an opponent controls.
Whenever one or more creatures die, mill a card and put a bloodstain counter on this enchantment. Then sacrifice it if it has five or more bloodstain counters on it. When you do, return target creature card from your graveyard to your hand.

Make Your Move

Destroy target artifact, enchantment, or creature with power 4 or greater.

Goblin Maskmaker

Whenever this creature attacks, face-down spells you cast this turn cost {1} less to cast.

Vengeful Tracker

Whenever an opponent sacrifices an artifact, this creature deals 2 damage to them.

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.

Mountain

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 deals 3 damage to each of your opponents and you gain 3 life.

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 token: Draw a card.")

Lightning Helix

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

Snarling Gorehound

Menace
Whenever another creature you control with power 2 or less enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Rune-Brand Juggler

When this creature enters, suspect up to one target creature you control. (A suspected creature has menace and can't block.)
{3}{B}{R}, Sacrifice a suspected creature: Target creature gets -5/-5 until end of turn.

Deadly Complication

Choose one or both —
• Destroy target creature.
• Put a +1/+1 counter on target suspected creature you control. You may have it become no longer suspected.

Plains

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 this creature is turned face up, create two tapped 1/1 white Dog creature tokens.

Swamp

Shadowy Backstreet

({T}: Add {W} or {B}.)
This land enters tapped.
When this land enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Repeat Offender

{2}{B}: If this creature is suspected, put a +1/+1 counter on it. Otherwise, suspect it. (A suspected creature has menace and can't block.)

Novice Inspector

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

Gadget Technician

When this creature 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.)

Shady Informant

When this creature dies, it deals 2 damage to any target.
Disguise {2}{B/R}{B/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.)

Sanguine Savior

Flying, lifelink
Disguise {W/B}{W/B} (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 this creature is turned face up, another target creature you control gains lifelink until end of turn.

Raucous Theater

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

Person of Interest

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

Felonious Rage

Target creature you control gets +2/+0 and gains haste until end of turn. When that creature dies this turn, create a 2/2 white and blue Detective creature token.

Slimy Dualleech

At the beginning of combat on your turn, target creature you control with power 2 or less gets +1/+0 and gains deathtouch until end of turn.

Public Thoroughfare

This land enters tapped.
When this land enters, sacrifice it unless you tap an untapped artifact or land you control.
{T}: Add one mana of any color.