Campaign Event
The Campaign Event is one of the types of Events that you can choose to perform during your turn's Event Phase.
As a bonus for having chosen the Campaign Event, every face-up card with non-zero Movement (normally creatures) gets the Move Action added to their action pool.
At the start of a Campaign Event, the turn player must choose one of their inactive zones to activate. This is done by putting a Summoning Token from the supply onto it. If they already have all 11 Summoning Tokens, they draw a card instead.
Then they can proceed to Actions as normal.
This is probably the first event a player will do, because at the very first turn they won't have creature zones available to do any Battle, nor enough resources to Rift Summon.