I'll keep this to grammar, punctuation, and proper phrasing only, without changing your plot, meaning, dialogue, or descriptions.
The battle had been going as she had planned. Due to the power of the shard, she was able to harness more energy from it to power herself.
Although, Kim noticed that some of her muscle fibres were tearing from her body, being overloaded by the shard's power. Her nervous system was breaking down, and there was no guarantee that she would be alive after this.
Nevertheless, she did not care. All had been lost, and this was her revenge for what she had built coming crashing down before her.
Well, it seemed death came faster than she anticipated. When she thought she had won, it unexpectedly slapped her in the face—or, in her case, went through her.
A malicious chuckle rang out from behind her, and the chilling echo of death came from behind her.
