The act of casting a magic spell. Often comes with visible manifestations of magic, such as glowing light particles, magical auras, runic magic circles, energy balls, etc being gathered and shaped in the caster's hand or a wielded tool.
Chanting spell incantations may also sometimes count, even if there is no overt visible manifestation of magic. This depends on context: most fantasy examples count, while people doing the same in a magic-less setting generally do not. Basically it has to be an actual spell (explicitly or implied in context) to qualify.
