Niche D20Discipline feats are a type of feat that represent your training as a caster. Upon gaining the casting class feature for the first time, a character gains a single discipline feat of their choice. Discipline feats each have their own sub-category of feat, and unless otherwise specified each sub-category can only be selected once; thus certain feats cannot be mixed together.
Many Discipline feats are also tagged as magic feats, and may be selected whenever a character could gain a magic feat.