It's a special Treasure card (i.e., it's not an Item, and it doesn't provide a persistent bonus, like
Hireling or
Really Impressive Title), so the following rules apply:
- It can be played at any time, unless the card says otherwise.
- When it is played, resolve its effects immediately.
- Discard the card.
Since the card doesn't provide any information when it may be played, we have to assume the general rule applies (i.e., it can played at any time), and therefore it can be played during combat. However, you can't play it when you're Level 9, since it would give you a level.