|Ar tonelico Qoga: Knell of Ar Ciel Boss|
An impressive, yet macho-looking Reyvateil, Mute is a direct subordinate to Akane, the Clustanian Supreme Commander, so therefore, you will encounter her many times during your travels, although most of them she will be in the hostile side. She is the most recurrent boss in Ar tonelico Qoga: Knell of Ar Ciel, and she is also the very first enemy you will face upon starting the game. You will also have EXEC_CUTYPUMP/. as the background music in most of your battles against her.
This battle just serves as a tutorial for the game's battle system, so feel free to take it easy to get yourself used to fighting. In Easy you shouldn't have many problems to defeat her, while in Normal, you should be fine as long as you get used to guarding and dodging Mute's attacks. However, in Hard, this battle is pretty much impossible to win and will condemn you to a Game Over due to three reasons: Aoto hits for too little due to Mute's monstrous defense, she can kill him in just a couple of attacks, and you have only three healing items to use. Therefore, if you intend to play the game in Hard, begin it first in any other difficulty and change it to Hard after this battle.
And while theoretically it's possible to win this battle in Hard, it would require not only lots of skill, but also of luck, as Mute sometimes doesn't flinch from attacks and can interrupt any combos you try to use against her.
This battle will take place immediately after entering the Stairway to Fallen Heaven for the first time. Due to story reasons, you will be forced to use Finnel in this battle as your Reyvateil, but as you also had to Dive into her prior to coming her, you should have programmed her with the Hyuma you gained in her first Cosmosphere level, which should make things easier.
As for Mute, she didn't change much from the first battle against her, but she did pick up a new trick: a Stored Attack called Lovely Magical Stick, which will cause large physical damage to a single character, possibly killing them. Therefore, whenever she begins charging it, make sure to interrupt her not only to prevent the attack, but also to gain a large Beat Up bonus for Finnel. Purging Finnel once and unleashing her Song Magic once should be more than enough to defeat her. As for the Light RT Bs accompanying Mute, don't pay much attention to them and concentrate on the main boss, although make sure to not allow any of the enemies to enter into Finnel's Heroine Field.
In this battle, you will be preventing Mute from hindering the activation of the DFP at the Moebius Factory, reason why her default EXEC_CUTYPUMP/. will be replaced by EXEC_EP=NOVA/., the DFP's activation song, in this battle.
In this battle you can use either Saki or Finnel, although due to Saki's prolonged absence, it's advisable you use Finnel instead. Mute didn't change much in comparison to how she was in the previous fight, although she is now accompanied by Advanced RT As. So just apply the same strategy as in the previous battle, although make sure to Purge your Reyvateil as far as you can to increase the Burst charge speed and shorten the battle as much as possible. A Burst percentage of around 20000% should unleash a Song Magic powerful enough to wipe out Mute and all of her cronies.
This battle will take place as soon as you set enter the Ogai Memorial Preschool, and also doubles as the tutorial for using Flipsphere.
Since you will have the privilege of being allowed to use the Flipsphere without clearing Saki's Lv. 4 Cosmosphere for this battle, that's everything you should be doing, as Mute is tougher than how she was in the Moebius Factory, is accompanied by three Advanced RT As, and you will have only Saki and Aoto for this battle, so try to make it as fast as you can: attack, defend, heal and protect Saki as much as you need until you can unleash the Flipsphere and annihilate all the enemies in the field.
While it's possible to win this battle without using the Flipsphere, it isn't really advisable to do so, given the conditions in which you will be fighting and Mute's monstrous resistances to everything.
In this battle, you will be facing a very enraged Mute, as she thought the party was taking her for a fool for pretending to be brainwashed to escape from the Slave District. Here, Mute is tougher than ever before, and if she manages to unleash her Stored Attack, you can be sure that the targeted character will drop dead from it, so always be in stand-by to heal everyone and try to interrupt the attack whenever she tries using it.
On the other hand, by this point you should have synthesized at least one or two of your party's Ultra Supermoves, so this would be the perfect time to put them to good use: once your Reyvateil has reached her Lv. 4 Purge and accumulated a Burst of 30000%, unleash one of these attacks on Mute to see how much damage it will do to her. If she is still standing after receiving all the attacks of that type you can unleash with your party, allow the Burst to recharge for a while and finish her off with a Flipsphere. As for the rest, the same advice given for the third battle against her can also be applied here.