Question, will the rewards stay in your inventory after the event ends? And if so, will they stay in your inventory if you leave the world (EG I get the buffs in W22 but leave them alone and don't try to use them till W30 for example)
The items will stay in your inventory until after the event ends, You are not able to stack items that are the same type/kind. The event items are world specific so they must be used on the current world that is being played.