How hould it change the game if ... ?

[NTJedi]

Originally Posted by Knai

But see, you've taken the enemy fortress by the time this would be an option, meaning it is now your own fortress. Unless you are suggesting destroying the fortress entirely with the enemy still in it, which forces a fight.

My suggestion of destroying the fortress via a spell would not require a siege or capture of the fortress or even any friendly units in the province. It could be done across the map as a ritual spell where only a scout is walking past the fortress. I figured this would be obvious since "spells" can only be casted using a lab.