(I'm so happy to be able to use Alastasia! I made the changes you suggest, and I underlined them.)
Name: Alastasia Mayvendel
Race: Half Human, Half Slime-kin.
Appearance: Alastasia normally appears like an average human combatant. In her base form, she stands at 5 feet, 8 inches, and weighs around 150 pounds. She has pale white skin, short and pulled back blonde hair, and purple eyes. Alastasia wears plate armor with chainmail exposed around her neck and shoulders. Across her armor, tiny holes dot the armor to allow her slime to pass through from anywhere. Bound to her waist with belts, she carries a small pouch on her right side and her sword/sheathe on the right. Strapped across her right gauntlet is a rectangular shield that runs up her forearm, extending around two inches past her knuckles. A thin pink tattoo starts below her right eye that flows down and stops at her neck. Under her armor, the tattoos appear again around her navel where her slime core would be located. When she melts part of her body, the area turns into a dense yet translucent pink gel. The slime is lighter than her normal state, but it holds its own weight and doesn't run or drip. When visible, her slime core appears as a dense purple sphere with tiny tubes jutting out.
Biography: Alastasia was never meant to be. Her mother, queen of a small nation of mostly mages and shamans, was barren. After endless hours of meditation and prayer, nothing worked. In desperation, she made a pact with an evil water spirit. The darkness entered her heart, and for the first time, the queen felt peace. Months later, Alastasia was born. In the eyes of her mother and "father," she was their miracle child. On the surface, she was to be expected, taking well to her teachings as crown princess. However, it became apparent that she was not fully human. Her skin would change color. Bruises healed within minutes. The people saw this as a manifestation of the elements, but the queen feared that her secret would come to light. The spirit had warped the once benevolent queen into a paranoid tyrant, threatening even her closest supporters. When Alastasia was thirteen, uprisings broke out across the land. The magic that filled the streets no longer lingered. Eris, Alastasia's personal bodyguard, saw the writing on the wall. She convinced the princess to leave with her.
Days after the two fled, soldiers were storming the castle; the mob’s wrath claimed the queen’s life. Although she was miles away, Alastasia felt a chill in her core. That night as she slept, an unknown voice called to her. It was the spirit, and he had returned to claim its daughter. He explained everything to Alastasia’s horror. She was no child of the elements; she was a monster. And with an outstretched hand, he spoke: “You are alone, and I am your master. Only I can make you whole. Serve me as your mother did, and I shall free you.” But she stepped back and swayed her head. This is not what her mother would have wanted.
When she awoke, Alastasia swore vengeance. She spent the next few years roaming the countryside with Eris, hunting for any trace of the spirit. At first, she was disgusted with herself and refused to tap into her monster side. But as the duo continued their quest, she befriended people of all backgrounds and ideals. She realised that her powers could be used for good. This was no longer about revenge or redemption. By the time she was twenty-three, she had mastered everything Eris could have taught her, and after a decade of searching, she found the spirit and destroyed it.
Two years later, Alastasia was resting at home in a countryside town when she heard rumors passing through. A fabled championship across the seas where combatants vie for glory. To the winner, a single wish. Her eyes were locked on the mirror in front of her. With each passing day, she could see more and more of her mother in the reflection. Deep within her heart, she wanted to see her mother again, if only for a brief moment. While others would have ignored the rumors, Alastasia simply could not let this pass. She packed up her belongings and headed out.
• BODY ARMOR: Alastasia wears plate armor with chainmail underneath. The chainmail is visible around her neck and shoulders, allowing for more flexibility in movement. Tiny holes are scattered across her armor to allow slime to run though. The metal is comparable to steel, but it’s lighter and enchanted to resist elemental magic (Save energy). This is mostly to soften the blow from smaller magical projectiles and prevent her armor from completely shattering from larger attacks.
• WEAPONS: Alastasia’s preferred weapon is a Hand-and-a-Half broadsword. Due to its design, she can use it with either her left hand or both. If she sings it with one hand, it allows for a quick strike while allowing her to block with her shield. If she attacks with both, she forgoes her shield for a more powerful strike. When not in combat, it’s sheathed on her right side. In case of emergencies, she has a backup dagger hidden in her pouch.
• SHIELD: To match her weapon, Alastasia has a shield strapped across her gauntlet. It’s rectangular in shape, spanning across her forearm and extending two inches past her knuckles. Leather straps hold the metal shield to her arm. The metal is just like her armor. Close to steel but lighter, magically resistant, and has tiny wholes in it. Because of its size and shape, it does not further impede her movement and allows her to wield her blade with both hands.
• CANTEEN: In case Alastasia’s reserves run low, she has a metal canteen with water. If used, it would restore a tenth of her body mass. This is held in her pouch.
• POUCH: A simple leather sack attached to her belt. This contains her canteen and hidden dagger.
Skills and Training: After fleeing with her bodyguard Eris, Alastasia spent the next decade roaming the country in search of her target. She’s comfortable using swords, knives, and shields with limited training in bows and spears. Over time, she’s learned to watch her enemy’s movements (muscle twitches, eye movements, etc.) With this, she can predict where an opponent may attack. This gives the illusion that her reflexes are faster than a peak human.
Biology: Due to the circumstances around Alastasia’s birth, she is biologically half-human, half-slime Parts of her body can switch between two forms/states. Regardless of state, Alastasia is affected by magic like normal. Fire burns, ice freezes, and so on. The only exceptions are water (mentioned below) and Energy. If Energy Magic connects with Alastasia, it will go straight through her and be more effective, likely damaging her core.
• HUMAN: This is Alastasia’s base form. She appears completely human, and her biology is identical to a regular human with a few exceptions. She does not have a brain, instead having a dense core near her navel. It roughly serves the same purpose, controlling her body, but it also stores and releases fluids to be used by her body. The core can hold roughly two-thirds a body’s worth of mass. While slight damage to her core can result in heavy losses of fluids, any major damage will be fatal. She also does not have lungs, unable to drown in normal water. However, if the water is dense enough or completely under the control of someone else, it can flood her body and prevent her from altering her form. If she runs low on fluids, she will not be able to use her abilities. Over time, she will become sluggish and dizzy before finally collapsing, paralyzed until she refreshes her reserves. While in her human state, if someone catches off guard and wounds her, she will bleed blood like a normal human.
• SLIME: Alastasia can melt parts of her body into a dense yet flexible pink gel. This process takes mass in the form of water to perform. While small applications of this will use next to no water, any extended or dramatic use will quickly eat into her reserves. Alastasia prefers to partially transform her skin to prevent trauma, but she can melt her entire body. If she decides to turn her whole body into slime, she will appear as a translucent mass of moving slime with her purple core visible. When fully transformed, her armor and equipment will fall to the ground, requiring her to reclaim it. While partially transformed, it will sit on top of her body as long as it's supported by her human skin. For example, if she turns her whole arm to slime, she will lose control the armor on her arms and hand, and the armor will dangle at her side. If she only transforms a small portion of her arm, as long as it isn't at a major joint or socket point, she will have control over her arm The transformation from the human tissue into slime form takes around two seconds. Changing her slime back into human tissue will take longer based on the size of the transformation, taking up to a minute. As stated before, the more body she transforms, the more resources it will take.
Alastasia can let small objects such as daggers, bullets, or arrows pass through any transformed parts of her body without injury. Anything larger, and she can prevent a fatality by transforming into slime, but this will rip a large chunk from her body as a cost. To absorb a large amount of water, Alastasia must have a significant part of her body in slime form, but any bodies larger than a pond can dilute her, risking the chance of her losing her core.(For the sake of the EC's, she should not be able to absorb any significant or otherwise excluded source of water generated by the arena. The same goes for water magically generated by other combatants unless stated otherwise.)
• Body Manipulation and Regeneration: Alastasia can change the composition of her body as stated above. While most of her transformations are conscious and willed, she can flinch and transform involuntarily. This is hastily done and inefficient, however, and can be abused by her opponents to fake her out. If Alastasia is damaged or missing part of her body, she can release fluid from her core to fill in any wounds. This is done by covering the damaged area with slime, then transforming it into regular tissue. Light scars or cuts will heal practically instantly. Anything larger will take more time to repair, up to a minute for a missing limb.
• Generation and Detachment: Alastasia’s main combat tool is her ability to secrete slime from her body out of the holes in her armor. Normally, she uses this to create a ball of slime in her gauntlet and give it a set of instructions. Once created, she can detach this from her body and throw it at the opponent and it will carry out whatever instructions it was given. Examples of instructions include binding the target’s arms or legs, covering their eyes, or suffocating them. For a sphere the size of a softball, the maximum effective range for this is about 20 yards, with her losing complete control over slime at 40 yards. As it grows larger, the effective and maximum range will quickly diminish. If the slime cannot complete its instructions or it falls outside her range, it will melt into a puddle on the ground. She’s able to reabsorb the leftover slime to partially refund the cost regardless of the current state of her body.
Absorption: Alastasia can break down and absorb organic matter into her body. Normally, this ability cannot be used as it requires a large volume of her pink slime to do this. However, as last resort, Alastasia can transform her whole body into slime and throw herself at the enemy. Her equipment will fall to the ground along with her slime core. The slime core will keep a small slime bubble around itself. The rest of the slime will attempt to wrap around and move within the prey, likely suffocating them in the process. Once the prey is completely covered with the slime, it will start to melt through all organic matter that it comes in contact with. A full absorption takes around three minutes or less if the process is uninterrupted and the target cannot struggle. The more the target struggles, the longer it takes. If successful, the slime will crawl back to her slime core. Then, the slime core will use a large amount of the water absorbed to quickly reform Alastasia, taking a minute for a full recreation. The rest of the water will be added back to her reserves. If it fails, Alastasia will be effectively dead as the attempt would use up all remaining mass in her body, her slime core just sitting in her armor. Inorganic matter cannot be absorbed this way. Additionally, she can absorb fluids from fallen corpses. The more damaged and spoiled the corpse is, the less fluid she regains.
Personality: After a decade of wandering the country, Alastasia shows a healthy scepticism towards anything she isn’t familiar with. She will try to respect others and give them the benefit of the doubt, but she will watch for any sign of danger. The slightest body movement can set her off. She’s comfortable with fighting and will stop at nothing to achieve her goals even if it means playing dirty.