Infiltrating the Black Temple
Look for Jubeka's mark on the main entrance of the Black Temple. Once inside, speak to Jubeka at the Temple Summit.
Description
It's clear that Jubeka's soulstone has lead you here to the Black Temple.
The question remains... why?
The only remaining option is to head inside and figure out why they were here.
Rewards
You will also receive:
For this quest, do not go to the instance portal. You are to continue down the road, from which you completed the prior quest, until you reach the main gate. Click on Jubeka's Mark to enter the Black Temple scenario, "Pursuing the Black Harvest".
Lots of comments can be found on the Wowhead page for this quest in regards to spec, talents, glyphs, and mechanics to beware of. I am also including what I believe to be one of the better YouTube video guides.
NOTE: After you have turned in this quest, you will no longer be phased to the Black Temple mobs. Jubeka's Mark will still be there should you decide to return to Jubeka Shadowbreaker and unlearn The Codex of Xerrath passive. She will charge you 500 gold for the service.
Quest Progression
Trivia: Blizzard originally planned to involve more in this quest chain with Demonstrate Your Power, The Eye of the Naaru and Awaiting the Black Harvest. These were datamined on the Patch 5.1 PTR, but they were never made available to the players. This is clearly seen when reading the description of the second one, which doesn't match the events of this quest page.
Well, it seems I can't see the skull on the gate. Any suggestions? I have used /reload ui, and it didn't work. That's pretty much all I did and know how to do. Help would be appreciated!