Siffed (10 player)

Activate the hard mode of Thorim.

Before Thorim can be faught, part of the raid must run a gauntlet to reach him. After 3 minutes Sif despawns. After 5 minutes the raid is wiped. Normal mode requires engaging Thorim between 3 and 5 minutes after the encounter is started. Engaging Thorim in less then 3 minutes forces the raid to fight both Sif and Thorim simultaneously and counts as the hard mode of the encounter.

If at this point you wipe, you will still be granted the Siffed achievement. If you manage to kill Thorim, you will also recieve the Lose Your Illusion achievement.

Sif cannot be killed, but does attack the raid with Frostbolt Volley, Frost Nova and Blizzard. She also removes the Touch of Dominion debuff from Thorim, increasing his damage by 66% and his health by 43%.

This is the hard mode of the Thorim encounter. Completing it requires your group to engage Thorim within 3 minutes of entering the encounter. The normal time is 5 minutes.

Sif also likely gives Thorim additional abilities or increases the difficulty of the encounter in some other fashion.

((EDIT: Or, not quite. You get this by engaging Thorim on hard mode. You gain Lose Your Illusion for defeating him when Sif is present))

I didn't realize there were man-^&*!s in this encounter...