Anti-Magic Garrison
Anti-magic garrison is an adventure map object, that can withhold creature troops. It works like normal garrison, but it prevents all spellcasting. A hero who attacks magic garrison can not cast spells in combat. Also, a hero located on the garrison square can not cast adventure spells, and if the hero is attacked, the battle will take place "inside" the garrison and no spells can be cast in combat. Additionally, spellcaster creatures can not cast spells.
Like garrisons, anti-magic garrisons are typically used in narrow passes to create obstacle, that can not easily be passed.