Fortune will give you +1 G, but only for use any turn after the initial play.
A very practical use of this Spell is to play it right before you end your turn, especially if you have nothing else you'd like to play for that turn. For example, If you are saving up for a card costing 6 or more at the start of the game, until you can generate 6G at once, Fortune can be used to help generate a little more.
Another usage of this Spell is to contribute towards Integrity's passive, which relies on you spending 5 or more G each turn. With this you can play any 1 or 2 cost monster by itself, and still trigger your passive without having to play cards you wouldn't want to normally.
- Golden Pile (by BlueKitty)