DevourDevour is a static ability. “Devour N” means “As this object enters, you may sacrifice any number of creatures. This permanent enters with N +1/+1 counters on it for each creature sacrificed this way.”
Some objects have abilities that refer to the number of creatures the permanent devoured. “It devoured” means “sacrificed as a result of its devour ability as it entered the battlefield.”
Devour [quality] is a variant of devour. “Devour [quality] N” means “As this object enters, you may sacrifice any number of [quality] permanents. This permanent enters with N +1/+1 counters on it for each permanent sacrificed this way.” (CR 702.82) 3 (As this creature enters, you may
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) any number of creatures. It enters with three times that many +1/+1
countersTo 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.)
Whenever this creature attacks, it deals damage equal to its power to up to one other target creature. Excess damage is dealt to that creature's controller instead.