Magic Disruptor

Your practice over dealing with spellcasters have reached to the point of excellence. Thus, you gain the following benefits:

-When you successfully damage a creature with your Mage Slayer reaction, the caster must make a concentration check. If they fail, the spell fails to function

-As a reaction, you can give yourself resistance to a damage that you take from a spell. You may do this equal times to your proficiency bonus. You gain expended uses back on a long rest.