Breath attack
Breath attack is a special ability typical for living dragons, but also for Firebirds and Phoenixes. It enables them to attack two consecutive hexes at once, making individual damage to both hexes. However, creatures that are two hexes wide do not suffer double damage from the breath attack. Although creatures with breath attack specialty cannot directly attack allied creatures, they can - similar to Liches' Death Cloud and Magogs' Fireball Attack - cause damage to allied creatures located on the second hex. In other words, breath attack will also damage the hero's own troops if they are standing directly behind the attacked hex.
Damage for each attacked stack is calculated separately. Black Dragons' hate against Titans works even if the latter suffered from breath attack. If your Black Dragons attacked by mistake Titans who are part of your army, they still will deal 150% damage.
Certain other creatures like Mighty Gorgons have an attack that visually looks like a breath attack, but does not have the same effect.
Creatures with breath attack:
