The Dark Portal begins the post-Warlords expansion launch quest chain in an instanced version of Tanaan Jungle, the Assault on the Dark Portal, itself the second half of the Warlords of Draenor intro experience. A "What's New?" window will appear the first time the player logs in after Warlords of Draenor has been launched and will start this quest. Should players close the window, Hero's Call Boards in all capital cities also offer the quest.
Speak with Archmage Khadgar at the foot of the Dark Portal in Blasted Lands.
Archmage Khadgar, hero of the Second War, is assembling a coalition of Azeroth's strongest to bravely step through the Dark Portal and stop the Iron Horde's invasion of Azeroth.
Champions who are interested in glory can meet Khadgar at the base of the Dark Portal in Blasted Lands.
Safety not guaranteed.
You will receive: 5 70
Looks to me like we ended up in the right place.
Take the standing port to the Shattershore in the Wizard's Sanctum in the Mage Quarter. From there, fly south to the Dark Portal and speak with Khadgar:
A second check appears:
After hitting accept, cinematic plays:
At expansion release, a projection of Khadgar was located in Stormwind's Trade District, Orgrimmar's Valley of Strength, and the Shrine of Seven Stars and the Shrine of Two Moons in the Vale of Eternal Blossoms, which acted the same way as the one in Blasted Lands. This was a means to easing server stress by spreading out the questers and not having all the level 90s of a realm suddenly show up in one spot.
Possessing this quest will block access to the Blasted Lands quests that follow the breadcrumb quest "Iron Horde Invasion!". You can either drop this quest to finish the Blasted Lands quests, or complete the quest chain through the Tanaan Jungle and then return to the Blasted Lands to complete the quest chain there.