Bloodthirst

Bloodthirst is a keyword ability attributed to the Gruul guild of the Guildpact set from the Ravnica block. It works by putting a number of +1/+1 counters on a permanent (so far only creatures) as it comes into play, if an opponent has been dealt damage that turn.

From the Comprehensive Rules:

• 502.50. Bloodthirst
  • 502.50a Bloodthirst is a static ability. “Bloodthirst N” means “If an opponent was dealt damage this turn, this permanent comes into play with N +1/+1 counters on it.”
  • 502.50b “Bloodthirst X” is a special form of bloodthirst. “Bloodthirst X” means “This permanent comes into play with X +1/+1 counters on it, where X is the total damage your opponents have been dealt this turn.”
  • 502.50c If an object has multiple instances of bloodthirst, each applies separately.

Rulings

• It doesn't matter how an opponent was dealt damage, or even who controlled the source of the damage. If your opponent was damaged by one of his or her own painlands, for example, a creature with bloodthirst you play later that turn will come into play with +1/+1 counters.

• The permanents either come into play with the counters or they don't. They don't come into play small and then get the counters.

Examples

• Gristleback - {2}{G}
  Creature — Beast
  2/2
  Bloodthirst 1 (If an opponent was dealt damage this turn, this creature comes into play with a +1/+1 counter on it.)
  Sacrifice Gristleback: You gain life equal to Gristleback's power.

• Skarrgan Pit-Skulk - {G}
  Creature — Human Warrior
  1/1
  Bloodthirst 1 (If an opponent was dealt damage this turn, this creature comes into play with a +1/+1 counter on it.)
  Creatures with power less than Skarrgan Pit-Skulk’s power can’t block it.

• Petrified Wood-Kin - {6}{G}
  Creature — Elemental Warrior
  3/3
  Petrified Wood-Kin can’t be countered.
  Bloodthirst X (This creature comes into play with X +1/+1 counters on it, where X is the damage dealt to your opponents this turn.)
  Protection from instants