Partial anti-magic field
Lvl 4 hazard
  • Anti-magic.

    At the start of every round roll a d8. The spells from the rolled spell school cannot be cast within this field.

    1 Fire

    2 Ice

    3 Lightning

    4 Wind

    5 Radiant

    6 Necrotic

    7 Earth

    8 No effect

Creatures afraid of spell casters often set this up as a room inside a dungeon, or as part of the defenses inside bases of non-spellcasters.

Remixed from

There is a way to disable the field. Maybe an item a monster is holding, a lever on the wall, or maybe a high enough arcana check can disable it for a round (or any other puzzle to disable it)

No way to disable the field in the middle of combat. OR spellcasters who accidentally cast a disabled spell take 2d8 damage. OR change the possible results to only the spell schools your heroes know.