Yogg-Saron is the final boss encounter of the Ulduar raid dungeon.

General notions

The Old God Yogg-Saron can be engaged after the defeat of General Vezax in Ulduar. Entering his room will begin the encounter (unlike many bosses in Ulduar his aggro radius is massive). It is a three phase encounter, beginning with defeating Sara with her own guardians, then defeating the Brain of Yogg-Saron and finally defeating the body of Yogg-Saron. At the beginning of the encounter players will receive a debuff with 100 stacks called "Sanity". If this hits zero the player will have lost their mind and will to Yogg-Saron and will both be a slave to his will and see their entire raid as Faceless Ones.

• Sanity - Indicates your overall level of Sanity. If Sanity reaches zero your mind will be permanently under the control of Yogg-Saron.

Guardian of Yogg-Saron's abilities

• Shadow Nova - Inflicts 25,000 shadow damage to any targets nearby when the Guardian of Yogg-Saron dies (including Sara).
• Dark Volley - Inflicts 8500 to 11000 shadow damage to the entire raid. Reduces healing effects by 25%. Lasts 10 seconds.
• Dominate Mind - Dominates the mind of the target, temporarily placing them under Yogg-Saron's control. Also reduces Sanity by 4%.

Sara's Abilities (Phase One)

Sara is unattackable in Phase One and casts these spells randomly on the raid and on the Guardians of Yogg-Saron.

• Sara's Fervor - Increases a friendly target's damage by 20%, but also increases damage taken by the target by 100%. Lasts 15 sec.
• Sara's Blessing - Heals a friendly target for 27000 to 33000, but causes 60000 Shadow damage over 20 sec.
• Sara's Anger - Inflicts 12500 Shadow damage every 3 sec, but increases Physical damage done by 12000. Lasts 12 sec.

Keepers' powers

Talking to the Keepers of Ulduar before the fight will cause them to aid you in the encounter. The less you have helping the harder the encounter will be but better loot will drop and special achievements can be earned. Specific Keeper abilities below:

• Speed of Invention - Increases all damage done by 10% and movement speed by 20%.
• Destabilization Matrix　- Mimiron channels a beam of titan energy that destabalizes the molecular structure of certain Saronite based creatures, reducing attack speed by 100% and casting speed by 300%. Cast on all mobs in the encounter.
• Resilience of Nature - Increases all damage done by 10% and healing received from all sources by 20%.
• Sanity Well - Freya conjures a Sanity Well that regenerates the Sanity of anyone who stands within it. Two of these green beams will be up the entire fight at the sides of the room.
• Fury of the Storm - Increases all damage done by 10% and total health by 20%.
• Titanic Storm - Thorim channels a storm of titan energy that periodically strikes at enemy targets with bolts of lightning strong enough to destroy weakened immortal creatures. Without Thorim the Immortal Guardians in phase 3 are unkillable.
• Fortitude of Frost - Increases damage done by 10% and reduces damage taken from all sources by 20%.
• Hodir's Protective Gaze - Allows Hodir to save a friendly target who sustains fatal damage by encasing them in a nearly impenetrable block of ice for 10 seconds. Hodir must rest after performing this action.