https://www.youtube.com/watch?v=DFZcl2vTtm8&t
Long ago, when plagues ravaged the land
One doctor made a pledge to rid the world of pain and suffering
But even the most ingenious mortal medicine could not stay the tide of disease
stay
to give a legal order that stops or delays (something)停止；延期；延缓
The judge agreed to stay =(halt) the execution.
tide
a large amount of sth unpleasant that is increasing and is difficult to control （难以控制的）恶潮，怒潮
There is anxiety about the rising tide of crime.
犯罪率日益增长令人忧虑。
And after working tirelessly for many years, even his dearest loved ones fell sick and bade their final farewell
bid sb farewell
~ (sb) good morning, farewell, etc. formal to say ‘good morning’, etc. to sb
I bade farewell to all the friends I had made in Paris.
I bade all my friends farewell.
Legends told of an Herblord in Chenyu Vale who could cure any illness known to mankind
The doctor sought the Herblord, but found only a white snake, its breathing weak and its power all but spent
“Sign this contract, and let our lives be joined. Then I will impart to you the secret art of healing”
“But be warned: This art will harm your own health”
an ability or a skill that you can develop with training and practice 技能；技术；技巧
a therapist trained in the art of healing
接受过治疗技术训练的治疗员
Letter-writing is a lost art nowadays.
当今尺牍是一种已消失的技巧。
Appearing confident at interviews is quite an art (= rather difficult).
面试时表现出充满信心是一门很高的艺术。
beyond your ken
If something is beyond your ken, you do not have enough knowledge to be able to understand it. [usu v-link PHR]
The subject matter was so technical as to be beyond the ken of the average layman.该主题专业性太强，一般的外行人很难理解。
Link to original
Television is an effective means of communication.
With means(ways) beyond human ken, the doctor could now reverse the process of death
And yet, the time still came to say goodbye, only now… the one departing was the doctor, his life force spent
His final act in life was to pass on the contract to his final patient: his favorite disciple
The disciple chose to dedicate their life to saving the lives of others…
And generation upon generation followed in these footsteps
cough cough
Since I inherited this contract, I’ve always respected the path taken by my predecessors
And followed it myself unquestioningly
That is, until… I tried to use the art to save my own disciple’s beloved
She begged me not to use up my own life force. She said that this art is a poisoned chalice, an evil and unnatural practice…
She did not wish to sacrifice one life for the sake of another, when both were lives she treasured
when
considering that
why use water at all when you can drown in it
—Stuart Chase
…Only then did it occur to me: Did I not suffer when my master passed away, just as patients’ families do at their loved ones’ deathbed?
Are not the lives cut short by this contract just as worthy of saving as any patient’s?
What is this contract to us? Medicine, or poison?
Alas, I no longer have enough time left to find the answer
I entrust to your care both Changsheng and this final question
May you find a remedy for this conundrum, which has ailed us so…
Time and again… No matter how much I try to warn them, or balance their qi, I can never save them…
And you? What’s your answer?
…If I abandoned the contract and left you without a host, what would happen?
host:
an animal or a plant on which another animal or plant lives and feeds
Hmm… I suppose I’d spend my final moments taking a nice nap on Mt. Yaojun
Then, I’d be reunited with my old friends, and your predecessors
Then it’s decided. If there’s a life in front of me that deserves to be saved
Why shouldn’t I do everything within my power to save it?
…sigh Once again, it’s the same answer
So be it. Close your eyes
…Who knows how many more people will take on this contract
to decide to do sth; to agree to be responsible for sth/sb 决定做；同意负责；承担（责任）
I can’t take on any extra work.
我不能承担任何额外工作。
We’re not taking on any new clients at present.
目前我们不接收新客户。
None. This contract… will end with me