Astute Combat Caster

You are a veteran of casting spells in the chaos of combat, keeping a cool head and reacting quickly to changing conditions, learning techniques that grant you the following benefits:

• Increase your Intelligence score by 1, to a maximum of 20.
• You have advantage on Constitution saving throws that you make to maintain your concentration on a spell when you take damage.
• When a hostile creature's movement provokes an opportunity attack from you, you can use your reaction to cast a spell at the creature, rather than making an opportunity attack. The spell must have a casting time of 1 action and must target only that creature.