Selesnya Signet

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.

Spitemare

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

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.

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}

Basilisk Collar

Equipped creature has deathtouch and lifelink. (Any amount of damage it deals to a creature is enough to destroy it. Damage dealt by this creature also causes you to gain that much life.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Phytohydra

If damage would be dealt to this creature, put that many +1/+1 counters on it instead.

Ripjaw Raptor

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

Needletooth Raptor

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

Wall of Essence

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

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.

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.

Darksteel Plate

Indestructible
Equipped creature has indestructible.
Equip {2}

Snapping Sailback

Flash
Enrage — Whenever this creature is dealt damage, put a +1/+1 counter on it. (It must survive the damage to get the counter.)

Gruul Signet

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

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.

Hungering Hydra

This creature enters with X +1/+1 counters on it.
This creature can't be blocked by more than one creature.
Whenever this creature is dealt damage, put that many +1/+1 counters on it. (It must survive the damage to get the counters.)