Trigger ability

A trigger ability (トリガー能力 Torigā nōryoku) is an ability whose effect occurs when a certain event or set of conditions, called a trigger (トリガー Torigā), occurs.

The three types of trigger abilities are:
 * abilities that start with the word "when"
 * abilities
 * abilities

Characteristics of trigger abilities include:
 * Trigger abilities may be triggered in the middle of an effect. However, it does not activate and resolve until the current effect ends.
 * When an effect ends, if there are both trigger abilities and rule processes pending, rule processes are handled first.
 * If multiple trigger abilities were triggered, the turn player's trigger abilities are resolved first. The turn player chooses the order in which their own trigger abilities are resolved, then the non-turn player chooses the order in which their trigger abilities are resolved.