In the Heart of the Storm: An Achten Tan short story
Blown off course by a storm, a pirate ship carried on the back of a giant Nudibranch takes shelter at an island where no island should be.
Fenn, the mage in charge of their creature transport, senses something is off, but the island's uncharted location is only the first sign of an ominous presence lurking out of sight.
The malevolent entity will force Fenn to make unbearable choices if he ever wants to see his home again.
* This is a prequel to The Bone Master: Book 2 in the Achten Tan series.
It's standalone and doesn’t contain spoilers, so you can enjoy it even if this is your first encounter with this series.*