An antonym for the word mentor might be deceiver, or liar. A mentor is one who guides, teaches or advises. So something opposite in meaning would be one who actively mis-guides, or falsely teaches. Pupil is not the opposite of mentor.
mentor.
Teacher
Another word for "advisor" is "mentor" in English.
Another word for saviour is "rescuer" or "deliverer."
'advises' is one word for 'giving tips. 'coaches' is another. a 'mentor' might mentor, with a leaning towards active guidance in the tip-giving. 'tutor' is possible.
It's the same- mentor.
You could use a mentor, or a teacher.
You can mentor me if you'd like
Mentor comes from a Greek word, same spelling, meaning 'wise advisor'
the mentor mentored the student.
Since that word is an eponym (a common noun made from a proper noun), the first mentor was clearly Mentor, the mentor of Telemachus.
MY MENTOR IS A VERY GOOD ADVISOR.