Yeah, I got a little tongue tied during an episode of the podcast and said Mentaur rather than Mentor. I made the joke that I should do it as a monster and listeners agreed. So here it is the Mentaur.
Hit Dice: 6
Armor Class: 6 
Attacks: Head Butt (1d8)/Trample (2d6)
Special: Knows More Than You; Anything You Can Do, I Can Do Better
Mentaurs are powerful, wise, and ancient creatures with the head of a bull, the upper torso and arms of a human, and the body of a horse. For some treasure or a service, they are train and/or advise character’s in any field. The more detailed or advanced the training, the greater the cost for the training, However if crossed, they can be deadly opponents with very long memories.
Knows More Than You: No matter what knowledge or skill a character has, the Mentaur is better.
Anything You Can Do, I Can Do Better: If a character uses any special class ability or casts a spell, the Mentaur will now know how to use that ability or cast that spell (once during the encounter). At the beginning of an encounter, the Mentaur will know 1d3 each random cleric and magic-user spells of 1st to 4th level( 1d4 determined randomly like I said).
There you go. Keep rolling those dice.