Suppress Magic
The magical person focus on another person they can see within 30 yards and prevent the target from using any of their magical abilities. If the mastery of the caster is lower than the mastery of the target they are attempting to suppress, the ability may not be completely blocked but lessened in power. The cast must be focussed and channeled to keep the block active. Distractions or performing any other task will break the channel and remove the block.