Tempest Keep: The Eye is a 25-Man raid, which will be introduced to TBC Classic once Phase 2 hits the Live Servers. Currently, the Phase 2 Patch in on the PTR, meaning it will not be far off. In order to be able to enter Tempest Keep: The Eye, players must have completed the attunement chain for the new raid.
The Phase 2 patch has just hit the PTR Realm a couple of days ago, so the Release Date is just around the corner! Just like it was in the Original TBC, the first Patch brings a lot of new Content and Features to World of Warcraft.
According to a recent announcement from Blizzard, the release of Phase 2 will be on November 12th, this year. Dire Maul, which was originally planned to be part ob Phase 2, has already been released a couple of weeks back. You can still expect a bunch of new content with Phase 2 release, though!