Castellus Temple F6 Boss

Is there an easy way to defeat them? The Male Seraph is killing my party members with his rotten magics Q_Q While the Female Seraph doesn't really deal quite much. The Mirror silenced my Terra in the first turn that i cant use his skills

Having Terra silenced at the very first turn is just bad luck ;w;
What are the classes of your party members? I recall you have Hacker!Terra and Witch!Hexia, but I just want to know so I can help with some strategy.

You probably might want to use Hacker!Terra's upgraded SR skill to give invisibility to your party members while everyone bursts them down. If you have Duelist!Capelle and Valkyrie!Zephiel, you can rush kill one of them hella fast. If Dragoon!Zephiel's your game, you might need to take a more defensive strategy with her Shirei skills. Adept!Capelle and Witch!Hexia seem to be kinda weak at this battle because of the mirror's Silence, but you can spam recovery skills and try to disrupt them. Reaver!Luze would help compliment the party's single-target burst, especially giving the team a massive power boost with her upgraded SR. If you chose Chaser!Luze, you can essentially help your Adept!Capelle and Witch!Hexia deal more damage with Corroding Bullet, and get some extra damage in with her SR, but also note you're running the same risk of being silenced.

If all else fails, try getting a bit more levels. Also try stocking up on Anti-Silence drops and All Cure Potions (if you can get your hands on those) ;o

My Party is actually Reaver!Luze , Hacker!Terra, Witch!Hexia , Duelist!Capelle and Dragoon!Zephiel. I somehow managed to win the fight by using Capelle's stun shot EX at the first turn and Hexia's State Extension EX on the next turn. Which allows me to quickly kill the male seraph first and slowly deal with the female one and lastly the mirror.