217
You bring to mind the words of the Brotherhood Spell Counterspell and focus on the lock as you quietly recite them under your breath. For a few moments the air crackles with static electricity; then you feel a calm descend: the sorcerous spell which once protected this door has suddenly evaporated.
Confident that it is safe to proceed, you unsheathe your weapon and use its tip to prise open the three lockplates, revealing their internal mechanisms. With the lock exposed, you set about the now-simple task of opening the door.