Nethergarde Needs You!

! Re: PATCH 6.0.2 !
If you're level 90 and phased to the invaded Blasted Lands, but wish to complete low level quests, speak to Zidormi (48.2, 7.2).

She will phase you to the old version of Blasted Lands.

This also shows the green version of the dark portal, which can be entered to access Hellfire Peninsula without the City portals. However, the reverse is not possible.

I thought the completion text of the quest was amusing, "Silithus, not such a great place, eh? We get a lot of you from there..."

Kind of a head nod from the designers to the fact that the only 55-60 zones in the game are Silithus and Blasted Lands, and Silithus wasn't redone for the Cataclysm. As a result, Silithus is one of the last relics of vanilla-style questing in the game- much more grindy and slow going exp wise than Blasted Lands. I can see a lot of people starting out in Silithus, doing a few quests, getting sick of it, and taking the portal to Blasted Lands. I know I did.

The quest giver will not offer this to you if you have any other 'Hero's Call' quests to Nethergarde. I had picked up Blasted Lands: The Other Side of the World in Winterspring & once I dropped that one, this quest was available.