"Low Hp and defense" That is not true. She just tanked a magical nuke to the face with her health alone. At least that is what you wrote on your post. Yasha just did everything she could. She sent an area denial attack that was easily and completely nullified by Senna's amulet, she sent a myriad of different shells and Senna was still able to dodge them even though Yasha was shooting from a hidden position, not counting her strongest and ultimate spell... killing many innocent bystanders, and it still was useless against her. completely and utterly useless. Senna on the other hand is simply killing everything on sight, with incredible agility while shrugging off Selena's curses, Selena's attack, Yasha's shots...

I don't know how she managed to literally ignore the shockwave, the explosion and all the shit Yasha sent to her... Nothing seems to even graze her, nothing seems to affect her.
I understand that your character has certain skills & etc, but even though... I don't know what to do anymore...
If I attack, nothing will happen. I don't want to kill your character. I never wanted. But I don't know what to write anymore!! I really don't know!!!!

I'll repeat: If someone manages to get Yasha by surprise, I will either kill or make her gravely wounded. Since she 'actually' has low hp and low def. Yasha is a huge menace due to her high damage output. But other than her speed (with the fly spell and her 'stealth' with the Perfect Unknowable spell) she has no means to defend herself. She is completely inept at melee combat.