Reactionary Defense

You use a shield with a finesse as a rogue wields a blade. You gain the following benefits while you are wielding a shield:

• If you aren't incapacitated, and are wearing Medium or Heavy armor you can add your shield's AC bonus to any Dexterity saving throw you make against a spell or other harmful effect.
• If you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage, you can use your reaction to gain resistance interposing your shield between yourself and the source of the effect.