Invisibility

Invisibility is a status effect which makes units and heroes not appear on their opponent's screen or minimap, and makes them unable to be targeted directly by the enemy. Invisibility makes the unit's model appear transparent, but clearly visible still for allies. If it is an allied hero, its dot on the minimap also turns into a ring for the duration. A unit can gain (usually temporarily, but not always) invisibility through certain spells, items or the Rune of Invisibility. Some units, like most wards have permanent invisibility and do not need to acquire it through other sources. Generally, a unit keeps the gained invisibility until the duration runs out, or they perform an attack or a spell or item cast. True Sight and shared vision allows a unit to see invisible enemies without dispelling the invisibility. True Sight makes the units appear transparent, while shared vision only shows a silhouette. Both make the unit directly targetable again, without dispelling the invisibility.

Fade time and fade delay
Most sources of invisibility require some time to turn the unit fully invisible. During this time, the unit is still visible and targetable.

The fade time is a short delay before the actual invisibility is applied, during which a unit's model appears transparent, but still visible to everyone. During it, the unit does not automatically attack nearby enemies, no matter if the auto attack option is turned on or not. It also stops attacking when an attack order was already ongoing. Unlike during the actual invisibility, during the fade time, the unit can cast spells or items and even attack without canceling the invisibility. During the fade time, the unit is not phased, even when the invisibility of the spell phases the unit.

The fade delay is also a short delay before the actual invisibility is applied, but has some significant differences. First off, during the fade delay, the unit's model does not appear transparent. Furthermore, the unit does not stop automatically attacking nearby enemies when the auto attack option is turned on, and the fade delay does not cause the unit to cancel an already ongoing attack order either. Unlike during the fade time, it is not possible to cast spells or items or attack during the fade delay without resetting it. During the fade delay, the unit is not phased, even when the invisibility of the spell phases the unit.

Unit behavior during invisibility
While invisible, a unit never automatically attacks any nearby enemy, not even when it is revealed by True Sight and being attacked. However, when issuing an attack ground order, the invisible unit attacks. Generally, the invisibility is lost upon reaching the attack point. For ranged heroes, this is upon projectile launch. Depending on the source, invisibility may or may not apply a phase effect on the unit.

As for spell casts, the invisibility is lost upon reaching the cast point of the spell. This means that spells with extended effects like or  do not cancel the invisibility upon each beam or pulse. Channeling spells do not cancel it either when going invisible after the channeling started.

All ranged attacks and most projectiles of abilities are disjointed by invisibility. It is enough for a unit to turn fully invisible even just for a split second as a disjointable projectile flies to fully disjoint it. However, some projectile abilities still affect invisible units, and some have other effects entirely. Invisible units are still fully or partially affected by spells which affect an area.

Abilities using invisibility mechanics
Invisibility consists of multiple different functions working together. The unit's visual appearance while invisible is determined by one function which changes their transparency. However, this function does not cause the unit to be considered invisible by other units or by spells. To be considered invisible, another function is required which determines how units and spells treat that unit. This is also why only some invisibility spells grant phased movement, because the it is another function on its own.

Since these are all separate functions, it is possible for spells to use some of the functions without using the other. The following abilities use some, but not all invisibility functions

True Sight
True Sight allows a unit to see invisible enemies that are in range. Some of the listed spells provide True Sight only during certain situations. Spells which provide shared vision are not listed here, since it is not actual True Sight. A list for that can be found here.

Some abilities provide True Sight immunity, which prevents True Sight from revealing the units.

Targeting invisible units
Most spells which affect an area usually affect invisible units as well, with some exceptions. Single target spells cannot target invisible units without the help of True Sight. Although shared vision renders the unit's model visible even during invisibility, it is not enough to allow single target spells to target them.

Spells which choose specific or random targets on cast behave inconsistently with invisibility. This includes all bouncing spells (e.g. ) and multi-target spells like and. The following such spells do not target invisible units:

1 Require. When upgraded, these spells can target secondary units, but ignore invisible ones.

2 Require a talent. When upgraded, these spells can target secondary units ,but ignore invisible ones.

3 These spells choose a new target if their current target dies. They do not choose invisible targets.

4 also includes the single strikes from  upgraded.

5 does not seek for invisible units. The area effect does hit nearby invisible units.

6 The secondary is not created on invisible enemies. The area damage does affect invisible units.

7 does not select nearby invisible enemy units to toss. The area damage does hit invisible enemies.

The following spells have mixed interactions

Turning invisible after cast
For most spells, it does not matter if the target turns invisible after the spell's effect already have begun. Their effects continue normally, regardless of the invisibility. There are exceptions to this.

All sources of invisibility disjoint projectiles. Even a split-second of vision loss caused by invisibility is enough to disjoint projectiles, even when regaining vision of the unit before the projectile reaches it. This disjoint does not happen when having True Sight over the unit.

Besides disjointed projectiles, the following spells behave differently when their targets turn invisible while they are active.