Arcbond

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

Pain for All

Enchant creature you control
When this Aura enters, enchanted creature deals damage equal to its power to any other target.
Whenever enchanted creature is dealt damage, it deals that much damage to each opponent.

Stuffy Doll

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

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}

Requiem Monolith

{T}: Until end of turn, target creature gains "Whenever this creature is dealt damage, you draw that many cards and lose that much life." That creature's controller may have this artifact deal 1 damage to it. Activate only as a sorcery.

Dawnsire, Sunstar Dreadnought

Station (Tap another creature you control: Put charge counters equal to its power on this Spacecraft. Station only as a sorcery. It's an artifact creature at 20+.)
STATION 10+
Whenever you attack, Dawnsire deals 100 damage to up to one target creature or planeswalker.
STATION 20+
Flying

Barbed Servitor

Indestructible
When this creature enters, suspect it. (It has menace and can't block.)
Whenever this creature deals combat damage to a player, you draw a card and you lose 1 life.
Whenever this creature is dealt damage, target opponent loses that much life.

Brash Taunter

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