A dragon’s fiery breath, a medusa’s petrifying gaze, a spectre’s energy drain, and a cleric’s use of positive or negative energy to turn or rebuke undead are supernatural abilities These abilities cannot be disrupted in combat, as spells can, and they generally do not provoke attacks of opportunity. Supernatural abilities are not subject to spell resistance, counterspells, or to being dispelled by dispel magic, and do not function in areas where magic is suppressed or negated (such as an antimagic field).
Using a supernatural ability (such as a cleric’s turn or rebuke undead ability) is usually a standard action (unless defined otherwise by the ability’s description). Its use cannot be disrupted, does not require concentration, and does not provoke attacks of opportunity.
Source: Player's Handbook
