Zookeeper Mechan

{T}: Add {R}.
{6}{R}: Target creature you control gets +4/+0 until end of turn. Activate only as a sorcery.

Bolt Bend

This spell costs {3} less to cast if you control a creature with power 4 or greater.
Change the target of target spell or ability with a single target.

Torbran, Thane of Red Fell

If a red source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 2 instead.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Arcbond

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

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.

Raptor Hatchling

Enrage — Whenever this creature is dealt damage, create a 3/3 green Dinosaur creature token with trample.

Mithril Coat

Flash
Indestructible
When Mithril Coat enters, attach it to target legendary creature you control.
Equipped creature has indestructible.
Equip {3}

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Kazuul, Tyrant of the Cliffs

Whenever a creature an opponent controls attacks, if you're the defending player, create a 3/3 red Ogre creature token unless that creature's controller pays {3}.

Darksteel Plate

Indestructible
Equipped creature has indestructible.
Equip {2}

Star of Extinction

Destroy target land. Star of Extinction deals 20 damage to each creature and each planeswalker.

The Walls of Ba Sing Se

Defender
Other permanents you control have indestructible.

Donna Noble

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
Whenever Donna Noble or a creature it's paired with is dealt damage, Donna Noble deals that much damage to target opponent.
Doctor's companion (You can have two commanders if the other is the Doctor.)

Wrathful Raptors

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

Backdraft Hellkite

Flying
Whenever this creature attacks, each instant and sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost.

Giggling Skitterspike

Indestructible
Whenever this creature attacks, blocks, or becomes the target of a spell, it deals damage equal to its power to each opponent.
{5}: Monstrosity 5. (If this creature isn't monstrous, put five +1/+1 counters on it and it becomes monstrous.)

Neheb, the Eternal

Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
At the beginning of each of your postcombat main phases, add {R} for each 1 life your opponents have lost this turn.

Spider-Punk

Riot (This creature enters with your choice of a +1/+1 counter or haste.)
Other Spiders you control have riot.
Spells and abilities can't be countered.
Damage can't be prevented.

Feldon, Ronom Excavator

Haste
Feldon can't block.
Whenever Feldon is dealt damage, exile that many cards from the top of your library. Choose one of them. Until the end of your next turn, you may play that card.

The Last Agni Kai

Target creature you control fights target creature an opponent controls. If the creature the opponent controls is dealt excess damage this way, add that much {R}.
Until end of turn, you don't lose unspent red mana as steps and phases end.

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.

Pyrohemia

At the beginning of the end step, if no creatures are on the battlefield, sacrifice this enchantment.
{R}: This enchantment deals 1 damage to each creature and each player.

Sun-Crowned Hunters

Enrage — Whenever this creature is dealt damage, it deals 3 damage to target opponent or planeswalker.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Frilled Deathspitter

Enrage — Whenever this creature is dealt damage, it deals 2 damage to target opponent or planeswalker.

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}

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.

Chain Reaction

Chain Reaction deals X damage to each creature, where X is the number of creatures on the battlefield.

Silverclad Ferocidons

Enrage — Whenever this creature is dealt damage, each opponent sacrifices a permanent of their choice.

Raphael, Ninja Destroyer

Raphael must be blocked if able.
Enrage — Whenever Raphael is dealt damage, add that much {R}. Until end of turn, you don't lose this mana as steps and phases end.

Needletooth Raptor

Enrage — Whenever this creature is dealt damage, it deals 5 damage to target creature an opponent controls.