You have Three Tree's ...
One: Offensive Magic
Two: Defensive Magic
Three: Physical Combat [This Includes both Unarmed and Weapon]
First Tree: May Learn Rank 0-Forbidden
Second Tree: May Learn Rank 0-4
Third Tree: May Learn Rank 0-2
Guild, and Racial Techniques have no Limitations.
As a general rule all rank 4 techs have a 1 rd cooldown. All rank 5 techs will have a 2 round cooldown and a -2 to rolls for 1 rd after use. This is per rank not per tech.