As a reaction, which you take 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 18 meters it must make a Will saving throw. It takes 2d10 psychic damage on a failed save, or half as much damage on a successful one.
You can increase the damage by 3d10 for each additional mana or psi expended.