Heart of the Night

If anyone is interested, the essence of the battle is quite simple. We destroy the ballista and the tent (so that it doesn't poison the phantoms). I also destroyed the catapult, but I don't know why because the castle was reduced to a fort, and it didn't have time to destroy all the walls. Therefore, you can get +2 turns with archers; I'll replay it now.

Reducing it to a fort is the least, the catapult will definitely move at least once. Next (this is usually if the central tower is destroyed) -
all walls and buildings on gold will be destroyed, the most difficult (this is if the catapult destroys everything in the battle) - it's all the same, but the upgraded dwellings will also become basic. This will not affect the possibility of rebuilding and the city level.

Aynurel also messed up; instead of casting "Pants" on the phantom, he cast "Slow" on it - everyone in the garrison was laughing.

Aynurel is designed this way - whether the player can level up properly by the time he arrives, so there are no scripts for him other than speeding up the machines.

The summon is needed here, ideally, just for the phantom.

The summon is also very good for the heavenly shield/wall - to defend the dragon and close the holes in the walls (it saves a lot against the last enemy with strong troop speed buffs)

Greta receives the Ring of Broken Spirit after the battle - will it be needed in any way later, or can it be sold?

The ring is needed for the quest, without which one necromancer will be very unpleasant). The quest is given by the witch, the same one who offers skills to choose from.