One Good Eye - A Misplaced Adventures Novel - Jen Bair - Bog

Taking over an island nation of pirates should be easy for Hettie Stormheart, First Daughter of the merciless Island Witch, but leading her coven of twenty-seven siblings who can't agree on anything is like herding drunken cliff pigs.
When a foreign diplomat warns of an invading lord threatening their way of life, Hettie's got to whip her sisters into fighting shape to defend their home, only the invading army is unlike anything they've ever seen: beast-like men and amphibious assassins who can swim circles around them.
To make matters worse, Hettie's only hope of victory is a cursed magical artifact: Deryl, a sentient eyeball who hates magic-wielders and is more annoying than all her siblings combined. But as Hettie struggles to keep her ragtag group of defenders together, a new adversary emerges. One more ruthless and unexpected than even the shadow beasts that hunt them in the dark.
With Deryl's help, Hettie must overcome the invading army and protect her home from those who seek to destroy it. The true cost of victory may be higher than she ever imagined, and the fate of the island nation-and the Daughters' Coven-hangs in the balance.