Character Mastery Help!Follow

You can put a percentage in whenever you want and you need to catch up, I got to 14 last night

It depends on what class you are.

For example a necro every 5 levels has a CM that gives their pet a weapon, you would definitely want to CM to unlock that. Up until 60 you will probably only want to deal with the ability CMs specific to your class, the stat boosting CMs wont have much effect until you reach the higher levels. Of course there are exceptions as a tank might want extra STA or AGI before then or if you're an Alc you will want as much poison resist as possible, but for most classes it's not worth it until you near the endgame.

Sorry I never really played a shaman past low levels, only CMs of theirs I remember buying was cannibalism which was mildly useful, it sacrificed health for a small amount of mana if I recall correctly.