Activation time, also referred to as casting time, is the length of time it takes for a skill to prepare before it can initiate. Skills that have an activation time stated in their tooltip will show a yellow cast bar on your screen, filling from the left to right during the activation, lighting up once the cast has finished (see picture). Many skills can be activated while moving, and certain skills have no activation time. Activation time can be affected by certain skills and (de)buffs. Certain skills cannot have their activation time canceled until or after a certain point during the casting time.[verification requested] All skills to date that have an instant activation, such as a charged mantra or switching of an attunement, can be cast in the middle of another skill. However, they behave differently when pressed midair. Some instant skills are castable there while others won't work.
Many skills have an aftercast animation after the activation time which is performed before the next skill or attack is executed. This can often be canceled by immediately pressing another ability or sometimes by stowing your weapon, resulting in more abilities used in shorter time.
Canceling a skill during its activation time will result in a short "interrupt" cooldown of 4 seconds. Skills that have an activation time but also an immediate effect (i.e. Stun break like Well of Precognition) will still go on full cooldown when interrupted to prevent abuse. Some skills with defensive properties (Healing skills, Evade skills etc.) will also immediatly interrupt the current skill when pressed.