World of Warcraft v4.2.0a to v4.2.2 EU Patch

Dungeons & Raids
Firelands
The visibility of Ragnaros' Dreadflame ability has been increased.
The size of Ragnaros' hit box during the final phase of the Heroic encounter has been increased.

User Interface
Raid Frames should now remember whether they were shown or hidden upon subsequent logins

Technical
Players using multiple accounts should now be available to be invited to a Real ID Party.
Updating a raid roster while in combat should no longer cause a client crash.
Attempts to purchase Arena Season 10 items should no longer sometimes cause a client crash. (Korea Only)