Invisibility

Invisible units and Heroes do not appear on their opponent's screen or minimap, and cannot be targeted directly. Invisible units can still be affected by some non-targeted spells, such as area attacks. However, certain abilities do not affect Invisible units, such as Earthshaker's Echo Slam. Heroes can become Invisible by using skills, the items Shadow Blade or Smoke of Deceit, or by activating a Rune of Invisibility.

Generally, Heroes remain Invisible until their Invisibility duration runs out, or they perform an action, such as attacking an enemy or using an item. Invisible units can still be revealed by units with True Sight.

All ranged attacks and most projectile abilities are disjointed by Invisibility. If a Hero is targeted with a ranged attack, and goes invisible while the projectile is in flight, it will not damage or affect them. Some projectile abilities will still affect invisible Heroes, and some will have other effects entirely.

Invisiblity effects also have a Fade Time incorporated in them. Fade Time is the time it takes for a hero to go invisible. During this time, the hero can still be targeted, although they will be partially transparent.

True Sight
True Sight allows a unit to see Invisible enemies that are nearby. All Towers have a passive True Sight built in, including the Fountains and Ancients. Heroes can obtain True Sight by purchasing a Gem of True Sight, or can use Sentry Wards or Dust of Appearance. Sentry Wards grant True Sight around themselves, while Dust of Appearance causes Invisible units to be revealed for its duration. Necronomicon Warriors also have True Sight at Level 3.