Cris Tales

Story related, can't be missed

This difficult boss fight occurs at the end of Ceniza. You will not have Christopher and and another party member of your choosing with you. Essentially, you can only use Cris bell, Zas, and one other that isn't Christopher in your party. On top of that, you won't be able to invoke time crystals! I would suggest that you give Cris bell all the speed increasing items you can and/or constantly cast the speed up buff on her. You will also want her to have full mp before the battle as she will be casting a lot. After the bosses split, you should focus on one of them. When they get healed, then use regression as Cris bell to keep the damage up. Both are immune to burn, but not poison. I unlocked the achievement about 16 and a half hours into the game.

Unmissable achievement.

This was the first real challenging fight in the game for me and others strategies didn't work. I suggest farming a little for money first, just enough for max weapons for crisbell, jkr, and zas. This should get you to about level 21. Equip a poison keychain and speed items on jkr.

The fight
To get this started you have to do a bit of damage to get them to split. Your first target should be the sister on the left, she is the fastest to defeat and you don't want to fight both for very long. The main attack I used was jkr's impact strikes, just spam A as fast as possible until you're in the upper yellow then tap slower so you never go into the red, this prevents any build up of heat. The bosses attacks do inflict heat so if you're at 70 plus heat use coolant or your party will get hit with a big 100 damage if you're to slow. Impact strikes are unaffected by defense and do just shy of 1/5 the enemies health. Crisbell is used solely for healing unless everyone is full then use speed increase on jkr. If you have the amber ring(5% hp every turn) equipped on anyone don't use renovatio on them, the ring will take priority and you lose the renovatio effect immediately. Use zas's normal attack(This was better than magic for me) and for healing when crisbell can't keep up. A lot of their attacks are pretty easy to parry or at least deflect except for the volcano back forward attack and the volcano syncro(focus on healing after this one). Once the left one is down the other will get rage witch will have them attack nearly every other turn. From here the fight becomes more manageable. Don't worry their attacks are very easy to parry and for me just switched back and forth between the two. Use the same strategy of impact strikes, healing and speed-ups, and zas's normal or syncro if available. When the boss is under 4/10 hp left she will use the fireballs to heal herself instead of attack so you may want to start going in the red with impact strikes to do more damage at the cost of more heat. Once she is down too the fight ends and you can enjoy a cutscene and achievement.