Psionophage

Your thoughts invade and unravel the minds of others, eroding their certainty until nothing remains but doubt.

Psychic Erosion. Once per turn, when you deal psychic damage to a creature, you can erode its mind, imposing a -1 penalty to its attack rolls, saving throws, and ability checks for 1 minute. This penalty stacks with itself, up to a maximum of -5. If the creature is affected by multiple instances of this effect, the duration resets to 1 minute each time the penalty increases.

Shattered Focus. Whenever a creature affected by your Psychic Erosion fails an attack roll, saving throw, or ability check, it takes 8d10 psychic damage.

Psychosomatic Twist. Your mastery of the mind allows you to blur the line between body and thought. When you deal psychic damage, you can choose for that damage to instead become bludgeoning, piercing, or slashing damage. Additionally, when you deal bludgeoning, piercing, or slashing damage, you can choose for that damage to instead become psychic damage. You decide the damage type when the damage is dealt.