FlyingFlying is an evasion ability.
A creature with flying can’t be blocked except by creatures with flying and/or reach. A creature with flying can block a creature with or without flying. (See rule 509, “Declare Blockers Step,” and rule 702.17, “Reach.”)
Multiple instances of flying on the same creature are redundant. (CR 702.9)
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) 1 (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 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.)
When this creature enters, it deals damage to any target equal to twice the number of Goblins it devoured.