As an action, you wrap yourself in a mantle of shadow. For the duration, any creature has disadvantage on attacks made against you. An attacker is immune to this effect if it doesn’t rely on sight, as with blindsight, or can see through darkness.
You can expend 1 additional mana to cast the spell as a reaction, which you use when you are hit by an attack or missed by 4 or less. The attacker must make an additional roll and use the worst result and the duration changes to the end of your next turn.