Spell breakers are blood elf and High elf units that excel at battling caster units. They appeared in the Warcraft III The Frozen Throne human campaign to aid Kael'thas. They are produced at the blood elf Arcane Sanctum. Some believe they are the primary guard and patrol units for the blood elf cities in the Burning Crusade.
The cunning blood elf spell breakers have mastered the arts of spellcraft to such a degree that they have become immune to the effects of even the most powerful magics. Coupled with their fierce combat skills, their spell immunity makes them implacable foes when facing magic-wielding enemies. However, the spell breakers' most astonishing ability is to actually steal their enemies' beneficial enchantments and grant them to their own comrades. This uncanny ability has turned the tide of more than one battle in the blood elves' favor.
The powers of the spell breaker are terrifying to those with knowledge of magic, for their blows shatter the mana from a spellcaster's body.
Spellbreaker bladesThis section concerns content exclusive to the Warcraft RPG, and thus is not necessarily canon.
The deadly, two-bladed swords of the spell breakers strike fear in the hearts of wizards and sorcerers. The blood elves' elite warriors employ these frighteningly effective weapons to execute outlawed spellcasters, necromancers, and other evil practitioners of magic. This blood-elven two-bladed sword is the bane of any evil spellcaster.
In World of WarcraftThis section concerns content exclusive to World of Warcraft.
The guards in the blood elf capital city bear a strong resemblance to spell breakers; however, they lack the phoenix mask. They are also not labeled as such and are considered standard issue foot soldiers like guards of other capitals and towns. It is most likely that Blizzard based blood elf guards after the spell breakers as the Spellbreakers are the most iconic front-line warriors of the blood elf troops. While the blood elf city guards in World of Warcraft may not themselves be spell breakers, they do have similar equipment to spell breakers. One of the primary spell breaker abilities (spellsteal) was introduced as a mage ability.
RPG classThis section concerns content exclusive to the Warcraft RPG, and thus is not necessarily canon.
Monster Guide makes reference to spell breakers as a class blood elves become, along with already existing classes in the RPG. Perhaps it is hinting at an inclusion of the class in a future RPG supplement.