Cast animation/Cast point

All abilities require the caster to spend a certain amount of time before the ability's effects are applied. This time window is known as Cast Point or Cast Time'. The length of the cast time varies per ability and is set for each ability individually. Generally, a specific unit's ability share the same cast point.

Once the cast point is reached, the ability applies its effects, goes on cooldown and expends mana. An ability's cast point or cast time is indicated by a green overlay on the ability icon, which swipes over it during the cast time of the ability.

This means when the unit gets interrupted by disables or their own actions before reaching the cast point, the cast is canceled, the ability's effects are not applied, the ability will not go into cooldown and will not use any mana.

The player also can manually stop the ability cast by issuing a Stop (S) or Halt (H) command. When the ability cast gets interrupted during the cast time, the visual cast animation ends as well.

Cast point is different than cast animation, as only losing vision of the target cancels cast animation.

Instant cast
Quite a few spells have an instant cast time, meaning their effects are instantly applied as soon as the spell hotkey is pressed (if they are not targeted) or a target is chosen for the spell (if they are). Spells which require no targeting at all may not interrupt channeling spells upon cast. If a spell is targeted (be it a unit, the ground or an area) it will interrupt channeling spells, even if its cast point is instant. As for spells which require no target, there is no set rule for which of them don't interrupt and which do, but most of the time, if a spell does not have a backswing, it does not interrupt channeling spells either.

All toggle abilities fall under this category. Toggle abilities have neither a cast point nor a backswing, and as such never interrupt a channel. This applies to most toggled items too, but some such as are not considered a toggle and as such can interrupt.

Spells which are tagged as "immediate" or "toggle" (tags can be seen below) can also be cast in-between chain-disables (e.g. into, or any disable which uses invulnerability into a periodic area disable like  or ), since these spells have the highest priority of cast order. These spells can also be cast after an Ancient has fallen, during the scoreboard phase.

Abilities with instant cast
There are 3 ways a spell can have an instant cast point: If it has the "DOTA_ABILITY_BEHAVIOR_IGNORE_CHANNEL" tag, the ability simply will not interrupt channeling spells upon cast.
 * Its cast point is simply set to 0, in which case it will still use a cast backswing.
 * It has the "DOTA_ABILITY_BEHAVIOR_IMMEDIATE" tag, which causes the spell to neither possess a cast point, nor a cast backswing.
 * It has the "DOTA_ABILITY_BEHAVIOR_TOGGLE" tag, which turns the ability toggle-able, meaning it neither uses cast point nor backswing either.

Items with instant cast
Items generally don't have a cast animation. This list contains all item spells that additionally have one of the 'immediate' tags.

Spell Steal
Анимация применения/Время применения 施法动作/施法点