Arcbond

Choose target creature. Whenever that creature is dealt damage this turn, it deals that much damage to each other creature and each player.

Stuffy Doll

Indestructible
As Stuffy Doll enters, choose a player.
Whenever Stuffy Doll is dealt damage, it deals that much damage to the chosen player.
{T}: Stuffy Doll deals 1 damage to itself.

Wrathful Red Dragon

Flying
Whenever a Dragon you control is dealt damage, it deals that much damage to any target that isn't a Dragon.

Blazing Sunsteel

Equipped creature gets +1/+0 for each opponent you have.
Whenever equipped creature is dealt damage, it deals that much damage to any target.
Equip {4}

Coalhauler Swine

Whenever Coalhauler Swine is dealt damage, it deals that much damage to each player.

Gisela, Blade of Goldnight

Flying, first strike
If a source would deal damage to an opponent or a permanent an opponent controls, that source deals double that damage to that player or permanent instead.
If a source would deal damage to you or a permanent you control, prevent half that damage, rounded up.

Imperial Recruiter

When Imperial Recruiter enters, search your library for a creature card with power 2 or less, reveal it, put it into your hand, then shuffle.

Truefire Captain

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Truefire Captain is dealt damage, it deals that much damage to target player.

Boros Reckoner

Whenever Boros Reckoner is dealt damage, it deals that much damage to any target.
{R/W}: Boros Reckoner gains first strike until end of turn.

Brash Taunter

Indestructible
Whenever Brash Taunter is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: Brash Taunter fights another target creature.

Mogg Maniac

Whenever Mogg Maniac is dealt damage, it deals that much damage to target opponent or planeswalker.

Howlpack Avenger

Whenever a permanent you control is dealt damage, Howlpack Avenger deals that much damage to any target.
{1}{R}: Howlpack Avenger gets +2/+0 until end of turn.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Ill-Tempered Loner

Whenever Ill-Tempered Loner is dealt damage, it deals that much damage to any target.
{1}{R}: Ill-Tempered Loner gets +2/+0 until end of turn.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Ill-Tempered Loner // Howlpack Avenger

Spiteful Sliver

Sliver creatures you control have "Whenever this creature is dealt damage, it deals that much damage to target player or planeswalker."