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