Undine

Undine, one of the Four Spirits, is the elemental spirit of water. She is stoic and prefers solitude. Erubetie is a close friend of Undine and both share many traits. Unlike Erubetie, however, Undine believes that coexistence between humans and monsters is possible. Undine also seems to have an ongoing rivalry with Salamander, calling the power of flame “simple and shallow”. “Deeny”, much like the other spirits, is often annoyed by Sylph and traps her in water bubbles occasionally. Residing in her Spring in the Noah region in Chapter 2, she is the third spirit to be recruited by Luka.

When Erubetie attempts to use her Melt Storm in rapid succession, Undine intervenes and protects Luka with Aqua Pentagon. Erubetie, knowing her best friend has a grudge on humans, leaves. Since Luka has already recruited Sylph and Gnome at this point, she agrees to test him. Undine requests Luka to use the powers of wind and earth. He does so, and earns her favor. In Chapter 3, Promestein places a barrier that forcibly sends Undine to Gold Volcano, a fire-based region, the opposite element of water, to weaken her. When Luka re-encounters and rescues her, she has vaginal sex with him so she can recover her energy using his semen.

She has an artificial counterpart, Grandine, created and mass produced by Promestein in order to combat her enemies.

Undine (1)
''“A spirit who resides in a cave under “Undine’s Spring”, out of view of the rest of the world. A long time ago it seems as though she appeared before humans, but now she’s a shut-in.''

''Hating the humans who pollute the waters of the world, she mercilessly preys on any who dare enter her terrain. Absorbing them into her body, she assimilates their body to become one with hers.''

''Though she dislikes humans, she seems to hold regrets that humans and monsters aren’t existing in peace as they did in the past. A close friend of the Queen Slime, Erubetie, they treat each other as equals. They also seem not to interfere with each other’s dealings.”''

Undine (2)
''“A spirit of water, with a cold and strict personality. Though she usually lives in peace in Undine’s Spring, she sympathized with Luka and lent him her power. Due to her own mastery of a Serene State, her combat capability is quite high. She seems to be at odds with Salamander most of the time inside Luka’s body.''

''A force of nature herself, the armies of the Heavens were unwilling to kill her and risk causing global catastrophes. It’s believed that Promestein’s fake spirits were also intended to eventually replace the original Four Great Spirits, enabling them to be killed.”''

Attacks
*Aqua Pentagon: Defense ability which creates a wall of water. She only uses this ability to defend Luka from Erubetie.

Aqua Shake: Normal attack.

Aqua Stroke: Normal attack.

*Aqua Prison: Triggers bind status.

Aqua Melty: Binded attack.

* Non-requestable technique

Battle Overview
She may not have many attacks, but unlike the other spirits, Undine hits extremely high. Immediately use Gnome, then Death Sword Chaos Star. She’ll use Aqua Prison on this turn, so struggle twice to break free.

Attack a few more times until she spends a turn telling Luka to use both the power of wind and earth simultaneously. With that, use Sylph. Both powers will be active together, and with that, Undine agrees to join Luka.

Do not attempt to whittle her HP down all the way, as she can drain his HP faster than he can recover it.

If he fails to pass her test and remains defeated, she holds Luka close to her body and does penetration (like the slimes, she technically lacks a vagina) while he sinks into her body. Like Erubetie’s method, he is killed and absorbed.

Evaluation
''“You escaped Erubetie... And ended up being melted away anyway. The digestion lovers thank you for your hard work. Undine is another opponent you can't fight on equal terms. If you try to fight normally, you'll be overwhelmed sooner or later. But Undine seems to want something from you. Perhaps if you listen to what she says, you might see the path. But you should summon Gnome the very first turn to protect yourself from damage, and to break out of a pesky bind attack. Now go, oh brave Luka. Once you get tired of being eaten, please try to remember your quest. ''“

Elemental Techniques
''“Indeed, you seem to possess the qualification to wield my power... The power of water is one to reflect the heart. Project your serene heart out of your self, forming a pure blade... There was once a swordsman who wielded all four spirits at once. He had a natural talent, but it still took him a year to wield the power of water. I wonder how long it will take you...?”'' - Undine

''“I feel a new power stirring inside me. It feels like water is gently flowing through my body... No, it's not just inside me... That flow is outside of me as well, as if I'm in the middle of a tide. It's the same as with the wind and earth... After borrowing Sylph and Gnome's power, I was able to feel the element itself. A while after being able to feel them, I was able to wield them... This flow, too... I'll need to get used to it before I can wield it... I can feel something like a flow of water, all around me...”'' - Luka

Water Wall
''“She went right through the wall of water and hit me anyway... All it feels like is the damage was reduced a tiny bit. What the heck is this!? It isn't useful at all! It seems like I shouldn't waste the SP on it... It does the same thing as the earth, only worse!”'' - Luka

“Undine, lend me your power!” - Luka

At level 1, Undine’s power uses to 2 SP to summon a thin wall of water around Luka, however it reduces damage by a very small amount (~10); far less than Gnome’s power. Useless, it should not be used at all.

Activating this skill will terminate all other active spirits.

Serene Mind
''“Alright, hurry up and get into a meditation pose. Then empty your heart to nothing. You idiot, if you don't train your heart, you can't use the power of water! If you can't do that, you'll never be able to reach Heinrich's level! Empty your heart, and entrust yourself to the flow all around you. Quit sulking, you idiot. You should have been able to dodge that easily if you had given your heart over to the flow. If you don't believe in Heinrich's teachings, all the other Heroes are going to laugh at you. If you can't do that, you'll never be be able to use the power of water!”'' - Alice

''“Suddenly, both Alice's previous warning and training flashes through my mind. The mental training I went through to control the power of water... I close my eyes and entrust my fate to the flow. As my mind clears, I feel another sense awakening in me. Th...This... I can sense the differing "flows" all around me. The flow of the air... The flow of sound... The flow of power itself... I take in all of those mixing streams into my heart. It feels like I've become one with the world itself... One with the flow of the world. Something huge is approaching me. As it moves closer and closer, it creates massive waves, disturbing the streams flowing into my heart. I easily dodge to the side, avoiding the attack. No... I wouldn't call it dodging... It's more like a leaf floating down a stream, simply pushed to the side. I see it... The flow...! I feel another wave coming, disturbing the flows around me. ...I can see it. I see the waves coming off of the Dragon's giant fang. Like a tiny leaf floating on a stream, I let the wave formed by her giant fang simply push me aside, evading her attack. Without even needing to think about it, I easily evade all of her attacks. Alice's training paid off... With this, she would never be able to slap me again... She attacks even faster, creating more massive waves all around me. Swaying side to side, I evade every one of her sharp attacks. Without even needing to think about it, my body is pushed aside before her attacks can connect. Entrusting my arm to the flow connecting me to the Dragon, I draw my sword and slice along it. ”'' - Luka

''“...Well? You are able to use the power of water, right? I saw the fight with the Dragon Girl. At that time, you gave your heart over completely to the flow. You need to take Undine's power inside you, and project your inner self into the world around you. Like that, you can connect to the flow around you....I see, good. It doesn't look like any attack will hit you as you are now....Good, that's it. When you're connected to the world, both your attacks and evasion are unmatched....But did you notice? Your SP is decreasing by one every turn. In other words, it's taking intense concentration to maintain that control....It seems like you understand it now. When you're using that power, you're basically invincible. But in turn, your SP decreases by one every turn. Once you run out, the power is cut.”'' - Salamander

“Take the flow into my heart...!” - Luka

Having being bitchslapped repeatedly by Alice, pressured by a Dragon Girl, and lectured by Salamander, Luka entrusts his mind and heart to the flow of the universe. At level 2, attacks taken will invoke Serene Movement, in which Luka moves like water flowing around obstacles and evades most (if not all) attacks at a 100% rate (however Granberia (3 and 4) and Alma Elma (3) can still hit him). However, this technique requires massive concentration and uses 1 SP per turn and cancels when he runs out.

Luka can use Serene Demon Sword to cancel Serene Mind before he runs out of SP. One of the most deadly strategies is to use Serene Mind, then Serene Demon Sword, using only 3 SP to deal more damage than Earth Rumbling Decapitation, then fall back on Sylph + Gnome + Earth Rumbling Decapitation/Meditation when SP runs low.

Blade of Still Water
''“Entrusting my arm to the flow connecting me to the Dragon, I draw my sword and slice along it. Slicing along the flow connecting us, I feel my sword easily connect with an unguarded part of her body....I didn't cut you with power, I just followed the flow. Another powerful wave is coming....That, too, I cut through, dispersing the disturbance of the flows.”'' - Luka

''“...I...Impossible...! My thick scales... Cut through like paper!? H...How can such a thin arm...? That doesn't make sense! R...Ridiculous! You can't cut flame!”'' - Dragon Girl

''“Then next try attacking. Not a special skill, just a normal attack....Good, that's it. When you're connected to the world, both your attacks and evasion are unmatched.”'' - Salamander

Normal Attacking under the influence of Serene Mind invokes Blade of Still Water, letting Luka's blade follow the flow. This attack is stronger than a normal attack, equal to a critical hit, though obviously it can't score one.

Serene Mind (2)
''“Even if the skills have the same name, our mastery of it is far different. Without clearing out that fog, your blade will forever be dulled!”'' - Granberia

''“...Your dreams will die here if you lose now. Your battles and pain will all have been for nothing....Then call me once again. That conviction in your beliefs will supplement your heart. With that desire filling your heart, it will blow away any fog still remaining. At that time, your serene mind will be unmatched! You're now able to completely use my power. Your SP won't be reduced by 1 every turn anymore. My power should be able to be used at the same time as the other spirits, too...”'' - Undine

''“Why did I pick up a sword? Someone like me who doesn't want to hurt others... I don't want to see humans and monsters fighting any longer. I don't want to see lives being lost for no reason... If I lose, nothing will change. I must win! There can be no hesitation in my heart! This is it... A perfectly serene mind... It's surprisingly more peaceful than before... It's as if time itself is gradually slowing down into nothing. This must be what Granberia is always feeling in battle... Now standing on the same stage as her, I see how she can be so powerful...” - Luka

“Calm my heart and mind...!” - Luka

When Luka is pushed to the edge during Granberia’s fourth battle, his determination further enhances his Serene Mind. At level 3, the power of water becomes compatible with the other elements, is not canceled by Serene Demon Sword, and uses 4 SP instead of ALL. However, the dodge rate will be significantly reduced. Blade of Still Water now stacks with Wild Lands critical hit damage.

The evasion rate of Serene Mind is calculated differently than Sylph: if Luka is attacked by a multi-hitter skill and Serene Movement triggers, the entire skill is avoided altogether.

Chapter 3
''Even without Undine, a Serene State can be obtained. Normal attack power rises, and avoidance increases. It seems particularly effective against monsters.''

''“A serene state of mind... I know that trick. You synchronize yourself with the air around you, seeing the enemy's movements as waves through it. It lets you almost see into the futures of their actions, and evade their blows. So if I control my thirst for blood and intent to the maximum, you won't be able to read anything. I am one of the few Angels who survived the fight with Heinrich. I am fully aware of that skill's weak points.”'' - Archangel Ariel

After defeating Archangel Ariel, Promestein seals up Undine, making her unusable. However, during the battle with Promestein, Luka manages to awaken Serene Mind on his own, with the exact same functions as Undine Level 3, but has a 2 SP cost instead of 4. This skill is still effective on monsters, but less effective on angels, which requires Fallen Angel Dance instead.

Trivia

 * Despite having higher combat experience than Sylph or Gnome, she has the fewest amount of attacks compared to the other Four Spirits.
 * Undine mentions that Heinrich took at least one year to master her power.
 * Undine is the only member of the Four Spirits who kills Luka upon failure. According to Salamander, it is tradition for the Spirits to kill their defeated opponents, but the killing may be more related to Undine’s grudge.
 * Undine is one of seven characters in the game to canonically have sexual relations with Luka. The other six are Meia, Sara, Alice, Gnome, Sylph and Salamander.
 * Undines, also called ondines, are elementals, enumerated as the water elementals in works of alchemy by Paracelsus. They also appear in European folklore as fairy-like creatures; the name may be used interchangeably with those of other water spirits.