I think one of the main points I was trying to make with the Goblins comes in Chapter 56, A Warning from Varina. Nibel gets the "feeling" for the last time in the book and the news is not good. Varina foreshadows a time when one of the Drugars will come for him.
Then the amulet tells him about the Goblins. Nibel is completely taken by surprise. Varina brings Nibel and Toad up to speed on upcoming journey. "Two of the Goblins are planning to return to their home clan."
"In the World of the Dark Elves?" gasped Nibel.
..."If the two succeed in the making the journey, they are not only going to seek the assistance from their clan counsel, they plan to lure Queen Sabronella of the Dark Elves to Medelia, then kill her. Other Dark Elves are sure to accompany her."
So other than these tantalizing tid bits that will be explored in Book Two, some of the consequences of the open door to the Underworld are being presented to the reader. (I'll go into the "Door to the Underworld") later.