Maybe I'm a noob and don't know how to take Conservatories.
For example, in the War of the Tower, players almost never build Aviaries on level 1; instead, they use Psychics. Moreover, there are enough Psychics in the castle even to reach the maximum number (see /topic/7744/, although there is slightly more Air and Water magic there, and Psychics can be upgraded, so a direct comparison is not entirely accurate).
However, for a Conservatory of level two and your troops, it will be sufficient with a margin, even without mass spells. And if you have a Pope with good stats and Blind, then I think you can even handle a level three map, unless they start spamming morale-boosting spells.