Does anyone know how to word an NPC Action that temporarily gives a creature vulnerability to bludgeoning damage? (Or if such a thing is even possible?) I know how to apply this manually as an effect (VULN: bludgeoning), or as a power on a PC sheet, but I'd really like to be able to do this right from an NPC monster sheet.
An example of the type of ability I'm trying to create: Brittle Bones. One adjacent creature gains vulnerability to bludgeoning damage for 1 minute.