|Attack:||Chain Lightning, Lightning Ball Barrage|
|Special:||Deals heavy damage to heroes up close, launches long ranged attacks against defenses|
This ghostly enemy possesses electrical beam attacks that deal very high lightning damage to any visible heroes, the moment he/she gets too close. These beams do not target defenses. Harbingers will keep their distance from whatever they are targeting. They prepare a four-volley lightning ball barrage over the course of ~7 seconds, then fires them for ~4 seconds. These projectiles ignore Reflection Beams and deal splash damage on impact. On some maps Harbingers can be tricked into going around tight corners and running into your defenses to attack something far away, but getting close to this enemy is ill-advised.
Harbingers are naturally lightning resistant. A Darkness Trap or Strength Drain Aura is required to be effected by such elemental attacks. They possess a very large health pool that can rival that of ogres. In the Infested Ruins and Tomb of Etheria, two maps added with the Final update, the Harbingers are poison-based instead. They naturally resist poison and their attacks inflict poison damage as well.
Like the Djinn, Sharken, and Goblin Copters, this enemy is announced when they spawn (in dark blue text). But unlike these enemies, Harbingers do not appear on non-native maps on Nightmare difficulty. However... they DO spawn on some CDT maps on Nightmare, where they do not on Insane difficulty and below, such as Coastal Bazaar.
- Deadly Striker Towers can snipe Harbingers from a distance, before they get close enough to throw lightning balls or electrocute heroes.
- Place minions in front your main damage-dealing towers (notably mage towers) to keep Harbingers away from stationary tower-buffing heroes, such as a Monk (w/ Tower Boost) or a Summoner (w/ two guardian pets).
- The Huntress and Ranger's invisibility allow them to get up close to Harbingers without taking damage. However, they will get electrocuted if an uncloaked ally is nearby.
Despite having difficulty-dependent map icons in color, a Harbinger's robe and hood will always be blue or green.