Have

Vengeful Creeper

Disguise {5}{G} (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 Vengeful Creeper is turned face up, destroy target artifact or enchantment an opponent controls.

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.

They Went This Way

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

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.)

Long Goodbye

This spell can't be countered. (This includes by the ward ability.)
Destroy target creature or planeswalker with mana value 3 or less.

Island

Jetsam

Each opponent mills three cards, then you may cast a spell from each opponent's graveyard without paying its mana cost. If a spell cast this way would be put into a graveyard, exile it instead.

Flotsam

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

Flotsam // Jetsam

Unscrupulous Agent

When Unscrupulous Agent enters, target opponent exiles a card from their hand.

Conspiracy Unraveler

Flying
You may collect evidence 10 rather than pay the mana cost for spells you cast. (To collect evidence 10, exile cards with total mana value 10 or greater from your graveyard.)

Burden of Proof

Flash
Enchant creature
Enchanted creature gets +2/+2 as long as it's a Detective you control. Otherwise, it has base power and toughness 1/1 and can't block Detectives.

Bubble Smuggler

Disguise {5}{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.)
As Bubble Smuggler is turned face up, put four +1/+1 counters on it.

Topiary Panther

Trample
Basic landcycling {1}{G} ({1}{G}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

Murder

Case of the Stashed Skeleton

When this Case enters, create a 2/1 black Skeleton creature token and suspect it. (It has menace and can't block.)
To solve — You control no suspected Skeletons. (If unsolved, solve at the beginning of your end step.)
Solved — {1}{B}, Sacrifice this Case: Search your library for a card, put it into your hand, then shuffle. Activate only as a sorcery.

Escape Tunnel

{T}, Sacrifice Escape Tunnel: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
{T}, Sacrifice Escape Tunnel: Target creature with power 2 or less can't be blocked this turn.

Swamp

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.)

Surveillance Monitor

When Surveillance Monitor enters, you may collect evidence 4. (Exile cards with total mana value 4 or greater from your graveyard.)
Whenever you collect evidence, create a 1/1 colorless Thopter artifact creature token with flying.

Evidence Examiner

At the beginning of combat on your turn, you may collect evidence 4. (Exile cards with total mana value 4 or greater from your graveyard.)
Whenever you collect evidence, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Hard-Hitting Question

Target creature you control deals damage equal to its power to target creature or planeswalker you don't control.

Undercity Sewers

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

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.")

Deduce

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

Forest

Unauthorized Exit

Return target nonland permanent to its owner's hand. Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Sanitation Automaton

When Sanitation Automaton enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Loxodon Eavesdropper

When Loxodon Eavesdropper enters, 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, Loxodon Eavesdropper gets +1/+1 and gains vigilance until end of turn.

Faerie Snoop

Flying
Disguise {1}{U/B}{U/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 Faerie Snoop is turned face up, look at the top two cards of your library. Put one into your hand and the other into your graveyard.