Hornet Nest

Defender (This creature can't attack.)
Whenever Hornet Nest 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.)

Pyrohemia

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

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

Saber Ants

Whenever Saber Ants is dealt damage, you may create that many 1/1 green Insect creature tokens.

Broodhatch Nantuko

Whenever Broodhatch Nantuko is dealt damage, you may create that many 1/1 green Insect creature tokens.
Morph {2}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Overgrown Armasaur

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

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.

Druid's Call

Enchant creature
Whenever enchanted creature is dealt damage, its controller creates that many 1/1 green Squirrel creature tokens.

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.

Silverclad Ferocidons

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

Cacophodon

Enrage — Whenever Cacophodon is dealt damage, untap target permanent.

Vrondiss, Rage of Ancients

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

Wall of Hope

Defender (This creature can't attack.)
Whenever Wall of Hope is dealt damage, you gain that much life.

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 or a creature it's paired with is dealt damage, Donna deals that much damage to target opponent.
Doctor's companion (You can have two commanders if the other is the Doctor.)

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.)

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.

Sporeweb Weaver

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

Ranging Raptors

Enrage — Whenever Ranging Raptors is dealt damage, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Trapjaw Tyrant

Enrage — Whenever Trapjaw Tyrant is dealt damage, exile target creature an opponent controls until Trapjaw Tyrant leaves the battlefield.

Flumph

Defender, flying
Whenever Flumph is dealt damage, you and target opponent each draw a card.

Ripjaw Raptor

Enrage — Whenever Ripjaw Raptor is dealt damage, draw a card.

Needletooth Raptor

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

Wayta, Trainer Prodigy

Haste
{2}{G}, {T}: Target creature you control fights another target creature. This ability costs {2} less to activate if it targets two creatures you control.
If a creature you control being dealt damage causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Spitemare

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

Imperial Ceratops

Enrage — Whenever Imperial Ceratops is dealt damage, you gain 2 life.

Apex Altisaur

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

Dromad Purebred

Whenever Dromad Purebred is dealt damage, you gain 1 life.

Metropolis Reformer

Flying, vigilance
You have hexproof.
Whenever Metropolis Reformer is dealt damage, you gain that much life.

Mogg Maniac

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

Zalto, Fire Giant Duke

Trample
Whenever Zalto, Fire Giant Duke is dealt damage, venture into the dungeon. (Enter the first room or advance to the next room.)

Sprouting Phytohydra

Defender (This creature can't attack.)
Whenever Sprouting Phytohydra is dealt damage, you may create a token that's a copy of Sprouting Phytohydra.

Bellowing Aegisaur

Enrage — Whenever Bellowing Aegisaur is dealt damage, put a +1/+1 counter on each other creature you control.

Fungusaur

Whenever Fungusaur is dealt damage, put a +1/+1 counter on it.

Defense of the Heart

At the beginning of your upkeep, if an opponent controls three or more creatures, sacrifice Defense of the Heart, search your library for up to two creature cards, put those cards onto the battlefield, then shuffle.

Kami of the Honored Dead

Flying
Whenever Kami of the Honored Dead is dealt damage, you gain that much life.
Soulshift 6 (When this creature dies, you may return target Spirit card with mana value 6 or less from your graveyard to your hand.)

Fiendlash

Equipped creature gets +2/+0 and has reach.
Whenever equipped creature is dealt damage, it deals damage equal to its power to target player or planeswalker.
Equip {2}{R}