Here is the full list of all 31 Aegis Defenders achievements.
Complete Area 6
Complete Area 5
Found Kobo and the Clarent
Rescued Shreya
Complete Area 4
Zula Joined the Party
Defeat the MadXArmor
Complete Area 3
Purchase 15 items
Obtained The Blood of A God
Defeat the (KS) Breath Dragon
Earn 50 RP from Dialog Choices
Complete Area 2
Kaiim Joined the Party
Defeat the Zanoh
Purchase 5 items
Collected 15 Relics
Killed 300 Enemies
Complete Area 1
Killed 200 Enemies
Discovered Aegis
Collected 5 Relics
Killed 100 Enemies
Bart Joined the Party
Clu Joined the Party
Collected All the Relics
Complete Game on Hard Difficulty
Complete Game on Insane Difficulty
Purchase all items
Complete an entire area without dying
Complete the game without dying