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.)
Creatures with power less than this creature's power can't block it.