Here is the full list of all 28 Black Skylands achievements.
Defeat Horos
Get All Weapon Mods
Defeat Ruth
Liberate All Islands
Defeat Kain
Find All Chests of Gold
Defeat the Devourer
Visit Swarm Territory
Defeat Rhoda
Obtain Steel Condor Crossbow
Defeat Blast
Get more than 17 000 Weapon Steel
Get more than 17 000 Ship Steel
Defeat Mort
Get 50 Weapon Mods
Get more than 6000 Weapon Steel
Defend the Moth Village
Liberate 10 Islands
Get more than 6 000 Ship Steel
Find 10 Chests of Gold
Defeat Crash
Find 5 Chests of Gold
Get 5 Weapon Mods
Get more than 1000 Weapon Steel
Get more than 1000 Ship Steel
Liberate Mills Island
Liberate 3 Islands
Complete the Prologue