Wizard – “Hope of Zephyr” [Campaign 6, Mission 5]

It doesn't necessarily have to be level 7. Gargoyles, for example, are quite effective. You don't need more than one stack on the wall.

Do they have immunity to Fireball?

Added after 7 hours 8 minutes
Haha, with a successful attack, Fidaen destroyed the wall on turn 2:DD

Added after 1 hour 17 minutes

Do they have immunity to Fireball?
PS It really does work:)
Added after 7 hours 8 minutes
Haha, with a successful attack, Fidaen destroyed the wall on turn 2:DD

Okay, I defeated the Overlord. For the battle with the wall, I only deployed stacks of levels 6-7, except for Zehir, for whom I deployed gargoyles with golems. In the final battle, only Fidaen's and Raileigh's troops suffered; the rest came out almost unscathed:)
PS Something glitched in the last battle with the Overlord; after watching the cutscene where the Overlord flees, the game doesn't end, and all the checkboxes in the mission conditions become unchecked