I don't have a ton of details for this story, and unfortunately mostly only remember details from the end of the story. I'm fairly certain that it was the first book in a series, and was hoping to find the rest of it.
I read this around ten years ago, and I think it was just a few years old then, though it may have been a bit older. So, probably published around 2000 at the earliest and 2008 at the latest.
I'm fairly certain that the main protagonist was a young female (either teen or younger) from a modern setting, sucked into a fantasy realm. While she doesn't have any innate magical skill, she has potential to learn magic, and there are hints that she'll need to become more powerful to eventually face the big bad of the series.
The protagonist has a mentor, also female, who is from the magical world, and may have been the one to bring her into it. Towards the end of the book they become separated, and the big bad turns the mentor into a figurine-sized wooden statue, and carries her off in his/her pocket.
The final "character" that I remember is perhaps the most unique detail of the book. This character is a blob of blue energy with magical properties. The blob was called Electrum or Elektra or something very similar to that (I'll call it E for convenience, since I can't remember exactly). I vividly remember the title to the chapter where E was introduced being "Enter E". I don't remember if it was sentient or not, but it became a constant to the protagonist, perhaps a gift from the mentor. At one point E was stretched out and used as a giant trampoline.
Like I said, the main character was from a fairly modern world, but there was a parallel/alternate world where magic is more commonplace.
There may have been a magical salamander (of the fire-making variety) either owned or captured by the big bad. The title of the book/series may have had something to do with keys.
I know that it's not a lot to go on, but it's been bothering me for a few years now, and I'd like to see if the rest of the series is out now so that I can see how the cliffhangers turned out.
I've looked under authors named Kay (because of the vague idea that it had something to do with keys), but nothing came of that.
I remember that I checked this book out from the Kent library in the King County Library System. I've looked through their catalog for YA Fiction published in those years, but again, nothing seemed to ring a bell, though I may have skimmed past it. I've contacted the library to see if there's a way to view my borrowing history back that far, which should hopefully help.
Now that I'm thinking about it more, the book may have been targeted towards a younger audience, so it might be listed as Youth or Juvenile Fiction instead of Young Adult or Teen.
The Library got back to me, and apparently when they switched to a new digital catalog system, they stopped tracking checkouts until I opted in, which I apparently did in 2010. I don't know what happened to records from before that, or if there even were records (I really want to make a pun about bad book-keeping). While I somewhat understand concerns about privacy, that means this route is a dead-end.