As a reaction, which you use when you are hit by an attack or take psychic damage, you absorb some of the incoming energy. You have resistance to psychic damage until the start of your next turn, including against the triggering damage. If the creature who damaged you is within 10 meters, it must make a Will saving throw.
On a failure, it takes 1d4 psychic damage and is staggered until the end of its next turn.
On a critical failure, it takes twice as much damage.
On a success, it takes half as much damage.
On a critical success, it takes no damage.
You can increase the damage by 3d4 for each additional mana expended.