The Court of the Blind King written by David Guymer.
Deep beneath the oceans of Ghyran, in kingdoms forgotten by gods and time and overlooked by the ravages of Chaos, the Idoneth Deepkin endure in bitter solitude. However, the Jade Throne of Briomdar sits empty, its long isolation threatened as never before in its history. The Everqueen’s warsong awakens the forests of both land and sea and everywhere the diseased knights of Nurgle fight to the last foetid breath for the verdant Realm they claim as theirs. But for Prince Lurien this time of peril is one ripe with opportunity. It will take every drop of wit, guile and treachery the prince has to overcome not only the myriad foes of the Idoneth, but his fellow Deepkin as well.