Arcane Combat Instinct

You have honed your body to react with magical precision, channeling arcane energy into every strike and parry. Your training blends spellcraft and combat into a single, fluid instinct. You gain the following benefits:

• Ability Score Increase. Increase your Dexterity, Constitution, or Wisdom by 1, to a maximum of 20.
• Instinctive Spellcasting. You learn the Shield spell. You can cast it once per long rest without expending a spell slot. If you already know or can cast spells, it counts as a known or prepared spell for you, and you can cast it using your spell slots as normal.
• Resonant Strikes. Whenever you hit a creature with a melee weapon attack, you deal an extra 1d4 magical damage. This damage is the same type as the weapon's (slashing, piercing, or bludgeoning) and counts as magical for the purpose of overcoming resistance and immunity.
• Arcane Counterstrike. When you cast Shield in response to an attack, you can make one melee weapon attack against the triggering creature as part of the same reaction.