As an action, you wrap yourself in a mantle of shadow. For the duration, any creature has disadvantage on attack rolls 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 or psi to cast the spell as a reaction, which you take when you are hit by an attack. The attacker must make an additional attack roll and use the worst result.