Mage Slayer (Revised)

You have practiced techniques useful in melee combat against spellcasters, gaining the following benefits:

• When a creature within reach of your melee attacks casts a spell, you can use your reaction to make a melee weapon attack against that creature. If the spell targeted you, or if it targeted an area you are in, you have advantage on this attack.
• 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 if you can notice the spell being cast (see page 85 of Xanathar’s Guide to Everything for rules on Perceiving a Caster at Work).
• When you take the Attack action on your turn, you have advantage on attack rolls when attacking a creature that has cast a spell in the previous or current round.