Magnus Chase and the Gods of Asgard #2; The Hammer of Thor by Rick Riordan

My name is Magnus, and I'm dead. My soul was sent to Valhalla, and now I'm a warrior with an amazing sword named Jack. Thor has lost his hammer, again, and giants will invade Midgard  unless he gets it back. Now, it gets complicated. Loki, the god of mischief, is trying to force his daughter, and my friend, Sam to marry a giant in order to get the hammer back. However, we're supposed to give the giant a devastating sword that will kill everything it cuts, before the giant will give us the hammer. Loki is in the middle of all this, so I know he has some devious plan in mind. He never does anything to help others, and he has no positive feelings for Thor. Sam's sister/brother Alex (it's hard to explain) wants to help, but I'm afraid Loki has an irresistible control over her.

You should probably read the first book in the series. This book is similar to the Percy Jackson books, but it has stranger humor. Jack is a deadly weapon that has the hots for other cute weapons. There's a dwarf with a keen fashion sense. All of the warriors in Valhalla practice killing each other every day (by actually killing each other) but are back in the cafeteria by dinner time. There's a god who likes to take selfies, and Thor plays air hockey in his man cave. A new character is Alex and he/she can change into other creatures. She/he also changes from girl to boy, and back, without knowing when it might happen. Charming characters for an adventurous plot. The conflict has huge consequences with the invasion of giants looming, but Loki's trickery is always on your mind. An entertaining book for lovers of mythological adventure stories.