when playing with the Halikarnassós wonder, in the A or B side there's one or more stages of the wonder that allows the player to go through the discard pile and pick a card for free and equip it.
Does this reward have to be used immediately or can you use it in a later age?
Example: you build the first two stages of the wonder on the first era. Can the reward of the second stage be used later in the third era?
No, it has to be used immediately at the very end of the turn it was built.