What is crowd control?

Crowd control (or simply, CC) is a term used to define an ability or spell that can temporarily reduces a unit's ability to fight. You do this by either restricting their contribution or means to escape. However CC does not make an enemy untargetable, even in cases of airborne effects the target is considered to be on the ground for the purposes of skill shots and area of effect damage (such as Karthus' Lay Waste)

Categorization

Crowd control is often categorized into two categories depending on whether or not the effect disrupts the channeling of an ability.

Hard CC — The following effects disrupt the channeling of abilities:

Airborne (Knockback, Knockup and Pull) Forced Action (Charm, Fear and Taunt) Pacify Silence Stun Suppression

Soft CC — The following effects do not disrupt the channeling of abilities:

Blind Entangle Slow Snare

Types of Crowd Control

Airborne: A unit that is airborne is unable to control their movement, attack or cast abilities for the duration. The duration of this CC is unaffected by crowd control reduction and cannot be removed by cleansing effects.

Knockback: A knockback causes the target to be made airborne in a direction away from the point of cast.

Knockup: A knockup causes the target to be made airborne on the spot.

Pull/Fling: A pull effect causes the target to be made airborne in a direction toward or behind the point of cast.

Blind: A unit that is blinded will miss their auto-attacks for the duration.

Charm: A unit that is charmed will attempt to move toward the source for the duration.

Fear: A unit that is feared will walk in random directions with reduced movement speed for the duration.

Taunt: A unit that is taunted will attempt to attack the source of the taunt for the duration.

Silence: A unit that is silenced cannot cast abilities for the duration.

Snare/Root: A unit that is snared is unable to control their movement for the duration.

Stun: A unit that is stunned is unable to control their movement, attack or cast abilities for the duration.

Slow: A unit that is slowed has reduced movement speed for the duration.

Entangle: A unit that is entangled can still cast spells but cannot move or auto-attack. Curse of the Sad Mummy is the only skill that applies this.

Countering Crowd Control - Prevention

Crowd control can be prevented. All forms of crowd control can be prevented, including knockback, knockup and pull effects.

Morgana's Black Shield prevents all forms of CC for 5 seconds or until the shield is broken.

Poppy's Diplomatic Immunity prevents all forms of CC for (6/7/8) seconds except from her target.

Olaf's Ragnarok prevents all CC for 6 second

Master Yi's Highlander prevents slows for (6/9/12) seconds.

Sivir's Spell Shield creates barrier for 3 seconds which can block the next enemy spell that hits her.

Nocturne's Shroud of Darkness creates al shield for 2 seconds which can block the next enemy spell that hits him.

Countering Crowd Control - Removal

Crowd control can be removed after it has been applied. These effects can be activated while under the effects of the crowd control.

All forms of crowd control can be removed except knockback, knockup and pull effects.

Cleanse removes all CC except suppression.

Alistar's Unbreakable Will removes all forms of CC

Gangplank's Remove Scurvy removes all forms of CC except blind.

Quicksilver Sash removes all forms of CC.

Garen's Decisive Strike removes all slows upon activation.

Countering Crowd Control - Reduction

Champions can also reduce the duration of crowd control effects. These effects stack multiplicatively or with diminishing returns.

Tenacity

The reduction from the Tenacity stat on items does not stack with itself and stacks multiplicatively with other types of CC duration reduction from the champion abilities.

Items that give tenacity:

Mercury's Treads Cloak and Dagger Eleisa's Miracle Moonflair Spellblade

Juggernaut reduces the duration of CC by 10%.

Cleanse reduces the duration of CC by 65% for 3 seconds (or 4 seconds with Summoner's Resolve ).