Abilities (also known as Spells or Skills) are unique skills that heroes, units, and buildings have access to, and can in most cases be seen in the bottom right of the HUD. The abilities can be innate or researchable, and can be controlled by the player (active), or automatic (passive). Casting abilities are the primary use of mana.
All heroes have four abilities total, which includes three basic abilities and one ultimate ability. The ultimate is always the last ability furthest to the right. When leveled up, heroes gain skill points up to a maximum of 10. Each basic ability has three levels, while the ultimate only one.
Time and Cost
All abilities have a cast time and cost, along with a cooldown.
Abilities use either the unit's cast time or its own unique cast time. The animation can be cancelled early to stop the ability from being used, and it will not spend Mana or go on cooldown if cancelled.
Instant Cast Time
Ignores cast time and activates instantly.
Will only provide its effect as long as the user does not get interrupted or cancel it early. Some forms of movement do not interrupt channeling.
The wait period after casting. The spell may not be allowed to be cast again until the cooldown time is over.
Mana Cost 
Requires Mana Points to be spent from your unit's mana pool. It cannot be cast without enough mana.
Some spells require a target to be cast, while other spells are released instantly.
Skills of this type do not require a target to be cast, and will activate when pressed. Skills of this type will start their effects as soon as their cast time or channel time has completed.
Skills of this type require a target to be selected to provide their effects. The cursor will change to allow target selection. The caster will move towards the target until it comes in cast range or the target can no longer be targeted.
Skills of this type require a point to be selected. Most Point Target abilities cannot be cast on cliffs.
Unit or Point Target
Some abilities are both Unit and Point Target. Targeting a unit will cause the spell to be cast on the point, where the unit stands, when the spell is cast.
Similar to Point Target a point needs to be selected, however a visual indicator appears to indicate the area that will be affected.
- Main Article: Active
Active abilities must be used in order to apply their effects. Active abilities can consume mana, cooldowns, and usually have some method of targeting related to them. Most abilities are active abilities. Active abilities are indicated by a bevel around the icon, which makes them look like a pressable button. They can be activated by pressing their associated hotkey.
- Main Article: Channel
Channeled abilities require the user to stay still while it is active. The effect ends if interrupted or cancelled. See the main article for a list of all channeled abilities and actives which can be used while channeling.
- Main Article: Passive
Passive abilities will apply their effects as long as they are available. Passive abilities do not consume mana and sometimes have cooldowns.
- Main Article: Aura
Aura abilities are similar to passive abilities, in that they don’t have cooldown or mana cost, but they will affect multiple targets in the area around the unit with the aura ability.
- Main Article: Toggle
Toggled abilities can change states between on and off. They are similar to passives but must be toggled to enable or disable their effects. Toggled abilities may have cooldowns and sometimes consume mana.
- Main Article: Autocast
Autocast abilities are abilities that can be toggled on to automatically cast, or turned off to manually cast. An auto-castable ability will have an empty rim around it, which glows orange when toggled on. When toggled on the ability will apply when it can.
- Main Article: Arrow
Arrow abilities look like Autocast abilities, but are just Orb Effects that can be toggled. See the main article for a more information about the difference between Autocast and Arrow abilities.
The ability type determines, whether a target can be targeted or not. It is similar to the Damage Type, which determines whether a unit can be damaged by certain damage source.
Most abilities are magical and cannot target spell immune units. They can however target ethereal units. Most magical abilities require Mana to be cast, but Devour Magic for example does not cost Mana.
Silencing abilities disable magical abilities.
Some physical abilities are disabled, while the unit is Ethereal.
Silencing abilities disable universal abilities.