A technique employed and founded by the Blademasters of Nimue. At it’s most rudimentary level is the ability to see the subtle flows of magic. Mastery of this has been used to shred spells like clothe, and even stop the casting of spells entirely.
It is however, an extremely difficult technique to learn, with one in every hundred talented students able to grasp it’s basics and only a few dozen said to have been true masters. While not truly magical in nature, the learning process does involve several rituals to induce heightened states of mind and alter perception. This is said to only be an aid to substitute for years of hermitage needed in the past.