Hello!
The legendary staff looted during the Kael’thas Sunstrider encounter in Tempest Keep - “Staff of Disintegration” is missing the on use effect. The staff seems to have lost its on use with stat changes of the cata prepatch.
No other legendary weapons from the fight are affected, but this is the single most important item for the encounter to immune the disorient effect that Kaelthas casts raid wide during the encounter.
Please upvote to bring attention as this makes the encounter nearly impossible due to constant disorient effects that are designed to be countered by this staff.