Assemble the Players

You may look at the top card of your library any time.
Once each turn, you may cast a creature spell with power 2 or less from the top of your library.

Deadly Cover-Up

As an additional cost to cast this spell, you may collect evidence 6.
Destroy all creatures. If evidence was collected, exile a card from an opponent's graveyard. Then search its owner's graveyard, hand, and library for any number of cards with that name and exile them. That player shuffles, then draws a card for each card exiled from their hand this way.

Archangel Elspeth

+1: Create a 1/1 white Soldier creature token with lifelink.
−2: Put two +1/+1 counters on target creature. It becomes an Angel in addition to its other types and gains flying.
−6: Return all nonland permanent cards with mana value 3 or less from your graveyard to the battlefield.

Plains

Novice Inspector

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

Due Diligence

Enchant creature
When this Aura enters, target creature you control other than enchanted creature gets +2/+2 and gains vigilance until end of turn.
Enchanted creature gets +2/+2 and has vigilance.

Kaya, Spirits' Justice

Whenever one or more creatures you control and/or creature cards in your graveyard are put into exile, you may choose a creature card from among them. Until end of turn, target token you control becomes a copy of it, except it has flying.
+2: Surveil 2, then exile a card from a graveyard.
+1: Create a 1/1 white and black Spirit creature token with flying.
−2: Exile target creature you control. For each other player, exile up to one target creature that player controls.

Swamp

Massacre Girl, Known Killer

Menace
Creatures you control have wither. (They deal damage to creatures in the form of -1/-1 counters.)
Whenever a creature an opponent controls dies, if its toughness was less than 1, draw a card.

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.)

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 token: Draw a card.")

Homicide Investigator

Whenever one or more nontoken creatures you control die, investigate. This ability triggers only once each turn. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Thinking Cap

Equipped creature gets +1/+2.
Equip Detective {1}
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Treacherous Greed

As an additional cost to cast this spell, sacrifice a creature that dealt damage this turn.
Draw three cards. Each opponent loses 3 life and you gain 3 life.

Shattered Sanctum

This land enters tapped unless you control two or more other lands.
{T}: Add {W} or {B}.

Perimeter Enforcer

Flying, lifelink
Whenever another Detective you control enters and whenever a Detective you control is turned face up, this creature gets +1/+1 until end of turn.