A reflex action is an action that may be taken during the reflex phase of a player. It may be taken the first time the conditions of its reflex trigger are met. Reflex actions and triggers vary and are listed on a model's card along with the reflex trigger.

If a player does not carry out a reflex action the first time it is valid, the player loses the opportunity to use it in that phase. Reflex actions are mandatory, and can be enforced by the active player. Where multiple models have reflex triggers they are carried out out one at a time, until either the reflex trigger is no longer valid or all reflex actions have been carried out. The player who is in their reflex phase chooses the order in which multiple reflex actions occurs.

A model can only carry out one reflex action per turn, unless stated by a trait or ability.  If a model can carry out multiple reflex actions, second and subsequent actions will be taken the next time the reflex trigger is met. The trigger for these actions may be met either by a new enemy model/action or by the same model which triggered the first reflex action.