Bloodthirst

Bloodthirst is a keyword ability. It appeared in the Ravnica block as the ability associated with the Gruul guild of the Guildpact set, and later also appeared in Magic 2012. 
==Description==
Bloodthirst was created by Brian Schneider. It works by putting a number of +1/+1 counters on a permanent (so far only creatures) as it enters the battlefield, if an opponent has been dealt damage that turn. Originally, Bloodthirst was a Gruul mechanic, limiting it to green and red cards. After a cameo in Future Sight it returned in Magic 2012, where it tilted towards black over green.
Spectacle is a similar effect from the Rakdos in Ravnica Allegiance. Another variant of the effect was printed in Innistrad: Midnight Hunt, where the Vampires had effects that triggered with opponents losing life rather than taking damage: <c>Mounted Dreadknight</c> has quasi-Bloodthirst 1 and <c>Vampire Socialite</c> gives the same to other Vampires cast. 
Bloodthirst rates at a 3 on the Storm Scale. It was poorly received during Guildpact due to being harder to trigger than it was on the return in Magic 2012, whence it was seen more favorably. With the payoff being a larger creature while requiring creatures attacking, the mechanic is broad and easy to develop.
==Rules==
==Rulings==
* Bloodthirst checks for any kind of damage, including combat damage.
* Life loss that isn't caused by damage (for example, the life loss caused by <c>Blood Seeker</c>'s ability) doesn't cause a creature with bloodthirst to get counters, but damage from a source with infect (a mechanic from the Scars of Mirrodin block) does, even though it doesn't cause loss of life.
* It doesn't matter who controlled the source of the damage dealt to your opponent. If an opponent was dealt damage by a source they controlled (such as <c>Manabarbs</c>, for example), creatures with bloodthirst that enter the battlefield under your control later that turn will get +1/+1 counters.
* The creature with bloodthirst enters the battlefield with the +1/+1 counters already on it. For example, a 1/1 creature that enters the battlefield with two +1/+1 counters on it will enter as a 3/3 creature, not as a 1/1 creature that then becomes 3/3.
* "Bloodthirst X" doesn't appear on any Magic 2012 cards.
==Examples==
==Creatures that grant Bloodthirst==
*<c>Bloodlord of Vaasgoth</c> (Vampire)
*<c>Twins of Discord</c> (Eldrazi)
==References==