Gurmag Swiftwing

Infest

All creatures get -2/-2 until end of turn.

Masked Blackguard

Flash (You may cast this spell any time you could cast an instant.)
{2}{B}: This creature gets +1/+1 until end of turn.

Mausoleum Turnkey

When this creature enters, return target creature card of an opponent's choice from your graveyard to your hand.

Spirit

Orzhov Racketeers

Whenever this creature deals combat damage to a player, that player discards a card.
Afterlife 2 (When this creature dies, create two 1/1 white and black Spirit creature tokens with flying.)

Parasitic Impetus

Enchant creature
Enchanted creature gets +2/+2 and is goaded. (It attacks each combat if able and attacks a player other than you if able.)
Whenever enchanted creature attacks, its controller loses 2 life and you gain 2 life.

Rakdos Trumpeter

Menace (This creature can't be blocked except by two or more creatures.)
{3}{R}: This creature gets +2/+0 until end of turn.

Clue

Ballroom

This land enters tapped.
{T}: Add {W} or {B}.
{4}, {T}: Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Ribbons of Night

Ribbons of Night deals 4 damage to target creature and you gain 4 life. If {U} was spent to cast this spell, draw a card.

Roofstalker Wight

{1}{U}: This creature gains flying until end of turn.

Spawn of Mayhem

Spectacle {1}{B}{B} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Flying, trample
At the beginning of your upkeep, this creature deals 1 damage to each player. Then if you have 10 or less life, put a +1/+1 counter on this creature.

Syndicate Enforcer

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Tithebearer Giant

When this creature enters, you draw a card and you lose 1 life.

Venomous Hierophant

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When this creature enters, mill three cards. (Put the top three cards of your library into your graveyard.)

Vindictive Vampire

Whenever another creature you control dies, this creature deals 1 damage to each opponent and you gain 1 life.

Chainwhip Cyclops

{3}{R}: Target creature can't block this turn.

Ravnica: Clue Edition