The Yogg-Saron encounter has received the following changes: Guardians of Yogg-Saron in phase 1 and Immortal Guardians in phase 3 have had their health reduced by 15% in heroic mode, the Destabilization Matrix cast by Mimiron will now correctly hinder the casting speed of Crusher Tentacles in both normal and heroic modes.
Immortal Guardians are now able to target players in the "illusion room" of Yogg-Saron with their summoning ability.
We're also in the process of deploying a hotfix for an issue with Immortal Guardians that could cause them to pause their movement before reaching melee range. This fix will also prevent the Immortal Guardian from running away if their target is stunned.