As a reaction, which you take when you see a creature within 18 meters of you casting a spell, you attempt to interrupt the spell. Make an ability check using your spellcasting ability. The DC equals the creature’s spell DC + twice the spell’s effective mana. If you have identified the spell being cast, you have advantage on this ability check.
On a success, the creature’s spell fails and has no effect.
A spell’s effective mana is normally the amount of mana it was cast with, including augmentation. If a feature lets a spell be cast without expending mana then the spell’s effective mana is its normal mana cost.
You gain a bonus to your ability check equal to 2 for each additional mana or psi expended.