Cleanse

Cleanse is a 'non-targeted' summoner spell. It is mainly used to remove crowd control effects to escape or catch a target. It cannot be used while suppressed but can remove most disabling debuffs. Unlike it reduces new debuffs after all current ones have been removed, making it a more effective escape mechanism.

Strategy
Cleanse can be used to escape when you receive a form of hard crowd control. For maximum effect it is advisable to either get high movement speed or couple this spell with or.

Trivia

 * Previously the tool tip stated that Cleanse was able to remove the Sleep debuff, although no such effect existed in the game.
 * The tool tip also explicitly mentions both immobilizes and snares, which are the same thing.