求不得

You can use a friend's Blade for this; both Ultimate and Follow up attacks work but he needs to be below 5% HP.

An "unfulfilled wish" refers to a desire, hope, or aspiration that has not been realized or achieved. It can pertain to various aspects of life, including personal goals, relationships, career aspirations, or experiences one hopes to have. The Chinese version of the achievement's title, 求不得, roughly translates to not getting what one wants. To put it simply: unattainability. This is most likely a reference to the eight sufferings of life, or the eight sufferings of Buddhism. They are as follow: 生苦 - Suffering of birth 老苦 - Suffering of old age 病苦 - Suffering from illness 死苦 - Suffering of Death 愛別離苦 - Suffering of the separation from loved ones 怨憎會苦 - Suffering of resentment and hate 求不得苦 - Suffering of not getting what one wants 五蘊熾盛苦 - Suffering of the flourishing of the Five Skandhas (the skandhas describe the components that make up the human experience and the illusory nature of a self. They are form, feeling, perception, mental formations, and consciousness.) Blade suffers from the 7th suffering, since he is unable to attain his wish. Blade's Wish is [Spoiler Alert].