When this creature enters, create a 2/2 white Knight creature token with vigilance, a 3/3 green Centaur creature token, and a 4/4 green Rhino creature token with trample.
2009-02-01"The number of Goblins it devoured" means "The number of Goblins sacrificed as a result of its devour ability as it entered." 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.
2009-02-01Voracious Dragon can devour any type of creatures, not just Goblins.