Since you're in Chapter 10...
For semi-immediate relief for the mana situation, you can cycle the daily prizes in the
Mischievous Therapy event until you arrive at the
Pumpkin Patch (3x3, day 8) or the
Phantom Bear (3x4, day 15) buildings, then proceed to try for those. They're rather poor in terms of mana output as compared to
Festival Merchant (4x3) building that you can craft from the Magic Academy, but it's something you can consider if you need something that might fit better in your city than your default mana-producing culture options in your tech tree. The amount of culture those two event buildings provide isn't something to sneeze at, tho.
One of the daily prizes in the event, however, is mana (day 11). Directly. Immediately gain mana. Not recommended to burn your event tokens on, but if you needed that mana
yesterday, then that's something to consider.
EDIT: As a comparison, the efficiency of the buildings at chapter 10 in terms of mana per hour per square is:
- Pumpkin Patch: 14.8
- Phantom Bear: 15.6
- Festival Merchant: 25