Cast Animation

Every unit has unique cast animations for each of their spells. The cast animation of a spell is enacted as soon as a target for the spell is chosen, if it requires one, or its hotkey is pressed, if it does not require a target. These animations are not bound to specific spells, but rather to the ability slots of each unit and hero. The length of the animations varies for each spell as each of them is unique and made for the spell which is usually in the slot the animation is bound to. Although "cast animation" only sounds like a visual part of the game, it does have a mechanical influence on the gameplay.

Every spell has a certain time frame the casting unit has to go through in order to successfully apply the effects of the spell. This time is commonly known as cast point or cast time. This cast time is set for each spell individually, and has nothing directly to do with the visual animation of the spells. However, since the animation starts playing immediately, it indicates the cast point of spells.

In almost every case, the length of cast animations exceeds the cast point of spells. Upon reaching the cast point, the animation does not stop immediately, but continues playing. For most spells, the unit keeps on standing still during this part of the animation, and is unable to act until the animation has completed, if it is not canceled. This is commonly known as cast backswing.

Channeled abilities
Unlike other spells, which go into backswing (if there is one) after reaching cast point, channeled abilities go into a channel after cast point. If the unit is interrupted before reaching the cast point, the spell does not start channeling and does not go into cooldown and use mana. Only after having reached the cast point will a channeled spell go on cooldown and draw mana. If a unit gets interrupted during the channeling, the channeling instantly stops. Channeled abilities necessarily do not have backswings, as the channel must follow the cast point where the backswing otherwise would.

Item abilities
Nearly all active item abilities are cast immediately once their hotkey is pressed or a target is chosen. Their cast point is either instant or exactly zero and they do not have a backswing.

Just like regular abilities, some item abilities do not interrupt the current spell animation upon using.

1 Toggling these does not interrupt. 2 Does not interrupt when targeting allies either.