Original text:
You say, 'Hail, Zermin'
Zermin says, 'Amazing! We can talk underwater?! Good. Do me a [favor] and I help you get out of here.'
Zermin looks around apprehensively.
You say, 'I will do you a favor'
Zermin says, 'Kill the giant mushroom locking my way out to escape, and I'll honor your favor. He has some guards, get rid of them as well.'
You have been assigned the task 'Zermin's escape.'.
Suggested changes:
You say, 'Hail, Zermin'
Zermin says, 'Amazing! We can talk underwater?! Good. Do me a [favor] and I'll help you get out of here.'
Zermin looks around apprehensively.
You say, 'I will do you a favor'
Zermin says, 'Kill the giant mushroom blocking my way out to escape, and I'll honor your favor. He has some guards, get rid of them as well.'
You have been assigned the task 'Zermin's escape.'.
Also ...
The phrase, "I'll honor your favor" is functional and grammatically correct, but just sounds awkward - at least to me. You could change this phrase to "I'll honor you" instead.