To Cultivate Immortality, I Have the Forbidden Technique Two-Way Foil

After becoming a useless person in cultivating immortals, I showed weakness on the surface and practiced forbidden arts secretly. My master scolded me for being stupid, my senior brothers thought I was a drag, and the whole sect regarded me as a shame. Until the demon king led his army to attack the situation, the master was wounded and dying, and the magic weapons of the brothers were all broken. I slowly took out the newly developed "Forbidden Spell·Two-way Foil", smiled in front of everyone's horrified eyes and said: "Start—the fairyland dimensionality reduction plan."