BloodthirstBloodthirst is a static ability. “Bloodthirst N” means “If an opponent was dealt damage this turn, this permanent enters with N +1/+1 counters on it.”
“Bloodthirst X” is a variant of the bloodthirst ability. “Bloodthirst X” means “This permanent enters with X +1/+1 counters on it, where X is the total damage your opponents have been dealt this turn.”
If an object has multiple instances of bloodthirst, each applies separately. (CR 702.54) 1 (If an opponent was dealt damage this turn, this creature enters with a +1/+1
counterTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) on it.)
SacrificeTo sacrifice a permanent, its controller moves it from the battlefield directly to its owner’s graveyard. A player can’t sacrifice something that isn’t a permanent, or something that’s a permanent they don’t control. Sacrificing a permanent doesn’t destroy it, so regeneration or other effects that replace destruction can’t affect this action. (CR 701.21) this creature: You gain life equal to this creature's power.