You have the Mage Slayer feat. MAGE SLAYER (Source: 5e Basic Rules) You have practiced techniques useful in melee combat against spellcasters, gaining the following benefits: • When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature. • When you damage a creature that is concentrating on a spell, that creature has disadvantage on the saving throw it makes to maintain its concentration. You have advantage on saving throws against spells cast by creatures within 5 feet of you.