Devour 1 (As this enters the battlefield, you may sacrifice any number of creatures. This creature enters the battlefield with that many +1/+1 counters on it.)
When Voracious Dragon enters the battlefield, it deals damage to any target equal to twice the number of Goblins it devoured.
2/1/2009 Voracious Dragon can devour any type of creatures, not just Goblins.
2/1/2009 “The number of Goblins it devoured” means “The number of Goblins sacrificed as a result of its devour ability as it entered the battlefield.” For each creature that Voracious Dragon devoured, this ability checks its creature type as it last existed on the battlefield to see if it was a Goblin at that time.