On Ashcour Island,
Before Aditya came to the Shadow Islands empire, Nathan, Amber, Josh, and Scott had already arrived in Zion City an hour ago. The four generals of the Istarin Empire were being an important task. Failure wasn't an option for them. If they failed, the enemy will be alerted and their chances of quickly conquering the Shadow islands Empire won't be successful.
The reason Aditya sent Josh, Scott, Nathan, And Amber for this mission was because of their abilities. Nathan was an assassin. This meant that he was an expert in hiding. By using his shadow Manipulation he can secretly move around Ashcour Island without making anyone suspicious.
Amber was an expert in illusion. She was the best illusion magic user that the Istarin Empire currently had. With her magic cultivation reaching beginner 4th-order, she now can use her illusion to hide from anyone except for 5th-order cultivators.