Timing of Spells & Abilities
You can normally play cards and activate abilities on your turn when there’s no combat occurring and nothing else is being played. But some cards have keywords that allow them or their abilities to be played at special times. these keywords mostly appear on spells, but can also appear on units, gear, and abilities.
Action: can be played on your turn as normal, but can also be played during showdowns, including during combat.
Reaction: Reactions can be played on your turn or during showdowns, but can also be played before another spell or ability resolves – so the Reaction resolves first!
Add: abilities that add energy or power, like the innate abilities of runes, can’t be reacted to. They happen immediately.