Rwolf is the first Master that you encounter in Breath of Fire IV. He has no special conditions for him to take you on as an apprentice. He teaches skills when the player reaches a certain amount of hits in a combo.
His Will ability, Haste, is good for letting slower characters have a better chance to combo, and seems to increase the parties alertness.
His skill requirements are reasonable and encourages the player to combine magic.
Rwolf has great skills (for the most part) and sets the tone for the other masters.