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.

Footlight Fiend

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

Havoc Festival

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

Thrill-Kill Assassin

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

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.)

Cryptborn Horror

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

Rakdos Signet

Carnival Hellsteed

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

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

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.

Rakdos Guildgate

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

Dreadbore

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.)

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, it deals 1 damage to you and you draw a card.

Macabre Waltz

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

Rakdos Firewheeler

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

Mayhem Devil

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