Channel

A channeled ability is an ability that can be interrupted by crowd control effects that inhibit casting (in addition to Death). These effects are: airborne, forced action, disarm, silence, stasis, stun and suppression. When the caster activates the channelled ability he stops any action he was performing at that moment.

While the effects of the ability are present the caster is channelling the ability. In most cases the caster can stop the channelling by performing any action, such as autoattacking, moving or casting their other abilities. Some channelled abilities, however, prevent the caster from doing anything else until the channeling finishes. Most activatable items and summoner spells can be used while channeling without interrupting.

List of Channeled Abilities

Champion	Ability	Channel duration	Notes
Caitlyn	Ace in the Hole	1 seconds	Channeling for the full duration is required to fire the missile. If the target dies while channeling, the ability is put on a 5-second cooldown.
Darius	Noxian Guillotine	0.25 seconds approximate	Darius is channeling during his dash. Darius must complete the channel in order to deal damage. Interrupting Noxian Guillotine does not put it on cooldown or expend mana.
Fiddlesticks	Drain	5 seconds	Deals damage every 0.5 seconds while channeling.
Fiddlesticks	Crowstorm	1.5 seconds	Channeling for the full duration is required to blink and start dealing damage.
Gragas	Drunken Rage	0.75 seconds	Channeling for the full duration is required to gain the bonus magic damage for Gragas' next basic attack within ~5 seconds. Gragas also gains damage reduction for 3 seconds.
Janna	Monsoon	3 seconds	Health is restored every 0.5 second while channeling.
Karthus	Requiem	3 seconds	Channeling for the full duration is required to deal the damage. While Death Defied is active, it is impossible to interrupt Requiem.
Katarina	Death Lotus	2.5 seconds	Damage is dealt every 0.166 seconds while channeling.
Malzahar	Nether Grasp	2.5 seconds	Damage is dealt to enemies in the Null Zone that is created upon starting the channel every second; interrupting the channel won't make the Null Zone disappear prematurely.
Master Yi	Meditate	4 seconds	Health is restored every 0.5 second while channeling.
Miss Fortune	Bullet Time	3 seconds	Damage is dealt every 0.25 / 0.2142 / 0.1875 second while channeling.
Nunu	Absolute Zero	3 seconds	Damage will be dealt even if the channeling is interrupted, but the damage will be reduced.
Ornn	Living Forge	4 seconds	Channeling for the full duration is required to purchase item.
Pantheon	Aegis Assault	1.5 seconds	Damage is dealt every 0.5 second while channeling.
Pantheon	Grand Starfall	2 seconds	Channeling for the full duration is required to teleport and deal the damage.
Twisted Fate	Gate	1.5 seconds	Channeling for the full duration is required to teleport.
Warwick	Infinite Duress	1.5 seconds	Damage is dealt every 0.3 second while channeling. The suppress effect ends early upon the channel being interrupted.
Rammus	Powerball	6 seconds	Gains movespeed while channeling. Upon collision deals damage and knocks back enemies. Enemies are then slowed for 1 second.

Movement Channels

The following abilities can also be interrupted by any form of crowd control that interrupts movement, namely: root and entangle, in addition to all those listed above.

Champion abilities

Champion	Ability	Channel duration	Notes
Caitlyn	90 Caliber Net	~0.25 seconds	Channeling for the full duration is required to dash.
Shen	Stand United	3 seconds	Channeling for the full duration is required to teleport.
Zac	Elastic Slingshot	0-Unknown seconds	The range increases over the first 0.9 / 1 / 1.1 / 1.2 / 1.3 seconds. The cooldown is reduced by half the base amount and half the health cost is refunded if the ability is canceled, interrupted or times out.

Other

Name	Duration of channel	Notes
Teleport	4 seconds	Channeling for the full duration is required to teleport.

Objective Channels

The following abilities can also be interrupted by taking damage (this does not include health costs). As of V4.4, shielded champions will still be interrupted even if the damage is mitigated.

Name	Duration of channel	Notes
Empowered Recall	4 seconds	Channeling for the full duration is required to teleport.
Recall	8 seconds	Channeling for the full duration is required to teleport.
Greater Relic	3 seconds	Channeling for the full duration is required to capture the objective.
Capture point	Varying duration	Channeling for the full duration is required to capture the objective. If the capture point is owned by the enemy, it will neutralize halfway through the channel.

Attacking Channel

Unlike other forms of channeling, Lucian's The Culling can be interrupted by attack-inhibiting crowd control effects rather than casting-inhibiting effects. These effects are: airborne, entangle, forced action, disarm, stun and suppression. The difference in the list is that silence is not present and entangle is. This is the only case of an attacking channel that does not inhibit movement.

Champion	Ability	Channel duration	Notes
Lucian	The Culling	0–2 seconds	Damage is dealt over the duration depending on the ability's rank.

Unstoppable Channel

The following ability can only be interrupted through Death:

Uniquely, Unstoppable Onslaught's is a channeled spell which additionally grants him a buff preventing CC from being applied to Sion. And even though the cast of Unstoppable Onslaught does not cleanse current crowd control, Sion can already not cast the spell when he is affected by the types of crowd control that would interrupt a channel (not unlike all other channeled abilities). Thus the channel cannot usually be interrupted.

There are a few exceptions, however:

Sion can still be interrupted by death, as with all other channels. If so, the effect will end as if he collided with a champion or wall, by dealing the AoE damage and CC effect around his current location immediately.

Due to a bug with Roar of the Slayer, Sion can occasionally cast his ultimate despite being snared. In that case, he will stand in place until the snare status effect wears off (In this time, the damage, stun duration and movement speed granted by the ability will still ramp up, and an enemy coming in contact with Sion will have them collide as normal).

The same bug allows Sion to cast his ultimate during most other hard CC aswell. If Sion starts charging while stunned, knocked up or silenced for example, the channel will be interrupted almost immediately, and Sion will perform the same leap as he does when the channel ends at maximum duraction (8s) or is ended normally via its second cast.

An allied trigger of the Blast Cone does not count as enemy CC and will thus disregard Sion's CC immunity, interrupting his ultimate. Sion will be turned in the direction in which he would be knocked into, then initiate the leap as if he has recasted the ultimate or was affected by enemy hard CC (see paragraph above), overriding the initial airborne effect of the plant.

Because Unstoppable Onslaught is a channeled spell, Kalista's Fate's Call will wait with its effect until the channel has ended, dragging Sion back to her across a potentially massive distance. Even though Sion will be dragged immediately after the channel ends, as he is still leaping if he didn't collide with anything, the AoE damage and CC effect still happen in the usual place of his would-be landing spot.

Champion	Ability	Channel duration	Notes
Sion	Unstoppable Onslaught	0–8 seconds	Damage and CC duration increase over the first 3 seconds of channeling. Not usually interruptable except through death, which has the same result as colliding with a champion or wall.

Charged Abilities

With the release of Varus, a new subtype of channeling was added to the game - charging. A charged ability has two activations - the first begins the charging and the second will fire the ability. While using quick cast, the player must keep the hotkey held down to charge the ability and it will fire upon releasing the key. Unlike casting channels, the caster is still able to move freely including the use of Flash and Dark Passage.

Charging is a sub-classification. The forms of crowd control that will interrupt a charged ability depends on the ability's supertype.

Champion	Ability	Channel duration/type	Notes
Pantheon	Comet Spear	0–4 seconds; classic channel	The damage is modified after the first 0.5 seconds, the range is capped after 1 second. Mana is half refunded if it times out, or is interrupted.
Pyke	Bone Skewer	0–2 seconds; classic channel	The range and crowd control is modified after the first 05 seconds. Mana is half refunded if it times out, or is interrupted.
Sion	Decimating Smash	0–2 seconds; classic channel	The damage and range increases over the duration, the crowd control changes passing the first second, and said new crowd control increases its duration over the last second. The cooldown is reduced to 2 seconds if the ability is interrupted.
Varus	Piercing Arrow	0–4 seconds; classic channel	The damage and range increase over the first 2 seconds. Mana is refunded if Varus cancels the shot or it times out.
Vi	Vault Breaker	0–4 seconds; movement channel	The damage and range increase over the first 1.25 seconds. The cooldown is reduced to 3 seconds and mana is refunded if the ability is interrupted.
Xerath	Arcanopulse	0–3 seconds; classic channel	The range increases over the first 1.5 seconds. Half the mana cost is refunded if the ability times out.

Casting Times

Most champion abilities that are cast (like Disintegrate) have a very brief casting time that will interrupt other actions, such as movement or attacking (most will automatically have the champion continue in their previous actions, although some will interrupt previous actions indefinitely). These casting times cannot be interrupted except by the caster's death. Casting times will show a channeling bar on screen, although the bars of short casting times will often not be drawn except on very high framerates.

Champions will ignore crowd control effects while casting, with the exception of displacement effects. This is different from crowd control immunity as the effect can persist the duration of the casting time. If a champion is knocked about while casting, the skill will still fire from the point of cast regardless of the caster's position at the time of fire (although it's worth noting that the animation will occasionally fire from the new location). For blinks and dashes, they too will move toward the selected target after the casting has finished regardless of crowd control effects suffered during the cast time.

"Casting" is sometimes referred to as "charging", although charging was assigned to a new mechanic with the release of Varus.

Some notable examples of longer casting times, or casting times that are frequently labelled bugs on account of their ability to ignore crowd control:

Champion	Ability	Cast duration	Notes
Ezreal	Arcane Shift	0.25 seconds	There is a wind-down animation upon landing, however this is not forced and Ezreal can move instantly.
Ezreal	Trueshot Barrage	1 second	Casting for the full duration is required to fire
Kassadin	Riftwalk	0.25 seconds	There is a wind-down animation upon landing, however this is not forced and Kassadin can move instantly.
Lux	Final Spark	0.5 seconds	Casting for the full duration is required to fire
Neeko	Pop Blossom	1.25 seconds	Casting for the full duration is required to fire. Does not interrupt any actions.
Tristana	Rocket Jump	0.25 seconds	Tristana cannot move or attack during the animation, but may use her abilities
Urgot	Fear Beyond Death (second cast)	1.5 seconds	Urgot can freely move while pulling but not while reeling the target. The channel can only be interrupted by Urgot's death.