Payment: EVENTS must be paid for at the time they are played. Event effects that cost additional CAPITAL must be paid for when the effect is initiated.
MODs: Modifiers can be played during your turn (unless stated otherwise) and are permanent unless destroyed, the "host" card is destroyed, or stated otherwise.
FLASHES: Flashes can be played at any time as long as you can afford it, and they have an immediate effect and short duration.
HAPPENINGS: Can be played during your turn, their effects are usually short in duration (instant, 1 turn/round), and then are removed from play.
OPERATIONS: Can be played during your turn, they last indefinitely unless destroyed or stated otherwise