The boss of A.I.G.I.S. is Metatron, a powerful angelic Persona. Metatron has no inherent weaknesses but is resistant to several elemental attacks. He primarily uses Almighty attacks, which cannot be resisted, and powerful Light and Electric skills. He also has access to strong healing and buffing abilities, making him a resilient opponent. Focus on consistent damage output and dispelling his buffs.
Metatron will occasionally summon 'Power' and 'Dominion' minions. These minions are weak to Ice and Wind respectively. Prioritize taking them out to prevent them from supporting Metatron and to gain Boosts for your party. Metatron can inflict 'Silence' and 'Fear' status ailments, which can severely hinder your party. Have items or skills to cure these (e.g., Amrita Soda, Patra). Utilize debuffs on Metatron (e.g., Tarunda, Rakunda) and buffs on your party (e.g., Tarukaja, Rakukaja) to gain an advantage. This is a battle of attrition, so resource management is key. Keep your HP high and chip away at his health.