If you've been dutifully logging in during Hearthstone's Hallow's End event in order to grab your free Arena tickets, you should know that you don't actually have to spend them during the celebrations.
The news was confirmed by game director Ben Brode on Reddit over the weekend.
Why might you want to hold onto them though? Well, for the duration of Hallow's End players get to choose an Arena hero as usual, but are then prompted to select a new Hero Power as well. It's a fun twist on the established format, but it's also made the Arena experience pretty imbalanced as a result.
If you're a purist who can't wait for things to return to normal when Hallow's End finishes on Monday 6th November, you can simply keep your ticket and enjoy a free run through the regular Arena when it returns.
Note that you do still need to log in during the promotional period to claim your free tickets - they won't be offered to you once Halloween's over.