As a reaction, which you use when another creature that you can touch or see within 10 meters makes an attack roll, an ability check, or a saving throw, you can hinder their effort. Roll a d4 and add the result as a penalty to the creature’s roll.
You can do so after the creature rolls but before any effects of the roll occur.
You can expend 2 additional mana or psi to roll 2d4.
You can expend 4 additional mana or psi to roll 3d4.