Trigger Effect Monsters

Trigger Effect monsters are a kind of Effect Monster in the TCG and HCCG.

Trigger Effect monsters have effects that activate in response to another action that just occurred in the duel; for example, when a monster is Summoned or leaves the field, or when a player draws a card or gains/loses Life Points. A Trigger Effect is activated as Spell Speed 1, even though multiple Trigger Effects can activate simultaneously and thus form a Chain.

Some Trigger Effects are optional and the monster's controller can choose whether or not to activate the effect at that time, while others are mandatory and must activate at the given instance. A Trigger Effect is considered optional when its effect description starts with the phrase "you can". However, if an optional Trigger Effect would activate while an already-existing Chain is resolving, it loses its opportunity to activate, a phenomenon that is known as "missing the timing". Mandatory Trigger Effects can never miss timing.

There are many Trigger Effect monsters currently in the game, including at least one member in every HCCG archetype.