The bonds of magic shatter like broken glass in the grasp of an experienced priest.
Mass Dispel is a level 42 priestability that dispels magic within a 15 yard radius of the targeted area, dispelling all harmful debuffs from friendly targets and 1 beneficial buff from enemy targets, affecting up to 5 friendly and 5 enemy targets.
As of the patch 9.1.0 hotfix on 2021-7-20, when Mass Dispel dispels multiple targets, the order of dispels is now random. Prior to this hotfix, the spell targets those closest to the center of the green targeting circle first and then moves outward.
For shadow priests, the mana cost of mass dispel is increased to 11.36% of base mana. This does not factor in the 80% reduction to shadow's mana pool size, causing mass dispel to cost more than half of the caster's maximum mana.
Patch 2.4.0 (2008-03-25): Increased the number of affected targets from 5 to 10.
Patch 2.2.0 (2007-09-25): Has a chance to be resisted when dispelling immunity effects. This will be displayed in the combat log. In addition, it will no longer cause rogues and druids in [Cat Form] to lose [Stealth]. The flashing area graphic has been removed.
Patch 2.0.10 (2007-03-06): Changed to always pick immunity-granting effects as its target. Note that even if [Ice Block], [Divine Shield], or [Banish] are dispelled by Mass Dispel, you'll still get an "Immune" message even though it has been removed.