Dragon Breath is a basic Magic ability. When activated the player hits all targets within a frontal cone for up to 188% of active spell damage. The damage is not affected by a target's use of a dragonfire protection.
Cleave is the Strength equivalent of Dragon Breath. However, Cleave hits for 125% weapon damage instead. Additionally, although it is the equivalent of Cleave, Dragon Breath only damages targets in the square directly behind the original target.
While wearing the Dragon Rider amulet, this ability's damage will be increased by 10% and it will have about a 5% chance to burn the opponent with a shortened version of Combust that does 10% of Dragon Breath's maximum damage three times.
Strangely, in PvP Dragonbreath can be used at a distance and generates adrenaline but does no damage. Against NPCs, Dragonbreath can only be used adjacent to the target. This was changed in March 2014.
Dragon Breath used to hit 300% active spell damage before a hidden update that severely weakened most abilities.
Even though that when using Revolution you need Dragon Breath for optimal damage. Most people prefer not to use this ability due to its short range.