The sliver is indeed in Droughtlands as affirmed by Amary above, in Redoubt to be exact. There is a Life Invasion there so be prepared and bring friends! Although, part of this sliver can be soloed if you are so inclined and want to just run in to check things out. When you zone in you will notice straight away that there are a LOT of mobs, and I do mean a lot of level 52 elites. And they look like they’re ready to tear you to shreds, so you want to tread carefully. You may also notice your new zone in quest.