Goblins, goblins everywhere.
Rats in the cellar is the classic entry level monster/quest. Our hero and their companions encountered the rats on level 1 in part four of the rhyme, so naturally, level 2 had to be goblins.
I tried to capture my sense of goblins. To my mind, they’re the proverbial gremlins of the Dungeons and Dragons world, even though there are literally gremlins. Clever, sneaky troublemakers. No great threat on their own, but in large numbers or by means of trap and trick, they can take down any party. Like a pack of psychopathic toddlers crossbred with piranha, and masters in the art of the ambush. They’ll eat just about anything that holds still long enough. That includes each other.