Anti-Magic Shell

Anti-Magic Shell is a level 57 Death knight ability that absorbs magic damage for 5 seconds. The caster is also immune to harmful magic effects for the duration of the shell. It does not, however, remove existing magic effects.

Background
Anti-Magic Shell was originally an ability available to Banshee units in Warcraft III. It has also appeared in World of Warcraft, where it was used by the Shadowfang Moonwalkers in Shadowfang Keep (as Anti-Magic Shield), and in Burning Crusade, where it is used by the Banshees in the Battle for Mount Hyjal raid instance.