Many
creatures have unusual
abilities. A special quality can be extraordinary (Ex), spell-like (Sp), or supernatural (Su).
Extraordinary: Extraordinary
abilities are nonmagical and are not subject to anything that disrupts magic. Using an extraordinary ability is a free action unless noted otherwise.
Spell-Like: Spell-like
abilities are magical and work just like spells, though they have no verbal, somatic, material, focus, or XP components. They are subject to spell resistance.
Spell-like
abilities usually have a limit on the number of times they can be used. A spell-like ability that can be used "at will" has no use limit. Using a spell-like ability is an
attack action unless noted otherwise, and doing so while threatened provokes
attacks of opportunity. A spell-like ability can be disrupted just as a spell can be.
For
creatures with spell-like
abilities, a designated caster level serves to define how difficult it is to dispel their spell-like effects and to define any level-dependent variable the
abilities might have. The creature's caster level never affects which spell-like
abilities the creature has; sometimes the given caster level is lower than the level a spellcasting character would need to cast the spell of the same name.
Supernatural: Supernatural
abilities are magical but are not subject to spell resistance. Using a supernatural ability is an
attack action unless noted otherwise. Supernatural
abilities may have a use limit or be usable at will, just like spell-like
abilities. However, supernatural
abilities do not provoke
attacks of opportunity and never require Concentration checks.