Arcbond

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

Illusory Ambusher

Flash (You may cast this spell any time you could cast an instant.)
Whenever this creature is dealt damage, draw that many cards.

Mogg Maniac

Whenever this creature is dealt damage, it deals that much damage to target opponent or planeswalker.

Sekki, Seasons' Guide

Sekki enters with eight +1/+1 counters on it.
If damage would be dealt to Sekki, prevent that damage, remove that many +1/+1 counters from Sekki, and create that many 1/1 colorless Spirit creature tokens.
Sacrifice eight Spirits: Return this card from your graveyard to the battlefield.

Coalhauler Swine

Whenever this creature is dealt damage, it deals that much damage to each player.

Ripjaw Raptor

Enrage — Whenever this creature is dealt damage, draw a card.

Forerunner of the Empire

When this creature enters, you may search your library for a Dinosaur card, reveal it, then shuffle and put that card on top.
Whenever a Dinosaur you control enters, you may have this creature deal 1 damage to each creature.

Body of Knowledge

Body of Knowledge's power and toughness are each equal to the number of cards in your hand.
You have no maximum hand size.
Whenever this creature is dealt damage, draw that many cards.

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.

Marath, Will of the Wild

Marath enters with a number of +1/+1 counters on it equal to the amount of mana spent to cast it.
{X}, Remove X +1/+1 counters from Marath: Choose one —
• Put X +1/+1 counters on target creature. X can't be 0.
• Marath deals X damage to any target. X can't be 0.
• Create an X/X green Elemental creature token. X can't be 0.

Overgrown Armasaur

Enrage — Whenever this creature is dealt damage, create a 1/1 green Saproling creature token.

Blasphemous Act

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

Rite of Passage

Whenever a creature you control is dealt damage, put a +1/+1 counter on it. (It must survive the damage to get the counter.)

Swans of Bryn Argoll

Flying
If a source would deal damage to this creature, prevent that damage. The source's controller draws cards equal to the damage prevented this way.

Hornet Nest

Defender (This creature can't attack.)
Whenever this creature is dealt damage, create that many 1/1 green Insect creature tokens with flying and deathtouch. (Any amount of damage a creature with deathtouch deals to a creature is enough to destroy it.)

Spitemare

Whenever this creature is dealt damage, it deals that much damage to any target.

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}

Inquisitor's Flail

If equipped creature would deal combat damage, it deals double that damage instead.
If another creature would deal combat damage to equipped creature, it deals double that damage to equipped creature instead.
Equip {2}

Orcish Bowmasters

Flash
When this creature enters and whenever an opponent draws a card except the first one they draw in each of their draw steps, this creature deals 1 damage to any target. Then amass Orcs 1.

Pestilence

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

Plague Spitter

At the beginning of your upkeep, this creature deals 1 damage to each creature and each player.
When this creature dies, it deals 1 damage to each creature and each player.

Sporeweb Weaver

Reach, hexproof from blue
Whenever this creature is dealt damage, you gain 1 life and create a 1/1 green Saproling creature token.

Vrondiss, Rage of Ancients

Enrage — Whenever Vrondiss is dealt damage, you may create a 5/4 red and green Dragon Spirit creature token with "When this token deals damage, sacrifice it."
Whenever you roll one or more dice, you may have Vrondiss deal 1 damage to itself.

Boros Reckoner

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

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.

Apex Altisaur

When this creature enters, it fights up to one target creature you don't control.
Enrage — Whenever this creature is dealt damage, it fights up to one target creature you don't control.

Truefire Captain

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