The mob "Scarshield Spellbinder" was added in patch 1.11.1, the Naxxramas patch, please either disable its abilities or remove the mob until Nax is released.
This is very important as when mind controlled the sizable fire resistance buff can then be cast on an entire raid and stacks with other FR buffs.
This dramatically decreases the difficulty of the Ragnaras and Vaelastrasz encounters, and removes the need for guilds to farm fire resistance.
Proof:
http://www.wowhead.com/npc=9098/scarshield-spellbinder#abilities%20-%20the%20mob
http://www.wowhead.com/spell=15123/resist-fire%20-%20the%20ability