Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Footlight Fiend

When Footlight Fiend dies, it deals 1 damage to any target.

Bedazzle

Destroy target nonbasic land. Bedazzle deals 2 damage to target opponent or planeswalker.

Bedeck

Target creature gets +3/-3 until end of turn.

Bedeck // Bedazzle

Thrill-Kill Assassin

Deathtouch
Unleash (You may have this creature enter the battlefield with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)

Mayhem Devil

Whenever a player sacrifices a permanent, Mayhem Devil deals 1 damage to any target.

Bladebrand

Target creature gains deathtouch until end of turn.
Draw a card.

Cryptborn Horror

Trample
Cryptborn Horror enters the battlefield with X +1/+1 counters on it, where X is the total life lost by your opponents this turn.

Rakdos Guildgate

Rakdos Guildgate enters the battlefield tapped.
{T}: Add {B} or {R}.

Blade Juggler

Spectacle {2}{B} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
When Blade Juggler enters the battlefield, it deals 1 damage to you and you draw a card.

Rakdos Signet

Dreadbore

Stab Wound

Enchant creature
Enchanted creature gets -2/-2.
At the beginning of the upkeep of enchanted creature's controller, that player loses 2 life.

Macabre Waltz

Return up to two target creature cards from your graveyard to your hand, then discard a card.

Carnival Hellsteed

First strike, haste
Unleash (You may have this creature enter the battlefield with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)

Havoc Festival

Players can't gain life.
At the beginning of each player's upkeep, that player loses half their life, rounded up.

Anthem of Rakdos

Whenever a creature you control attacks, it gets +2/+0 until end of turn and Anthem of Rakdos deals 1 damage to you.
Hellbent — As long as you have no cards in hand, if a source you control would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Gobhobbler Rats

Hellbent — As long as you have no cards in hand, Gobhobbler Rats gets +1/+0 and has "{B}: Regenerate Gobhobbler Rats." (The next time it would be destroyed, instead tap it, remove it from combat, and heal all damage on it.)

Rakdos Firewheeler

When Rakdos Firewheeler enters the battlefield, it deals 2 damage to target opponent and 2 damage to up to one target creature or planeswalker.