After accepting the quest, Charen will follow you as you make your way south to a spot near the portal to The Shattered Ravines. Once you get there, keep your distance. If you get into Rebirther Jirath's aggro range, he will flee into the portal and you will fail the quest. Wait until Charen approaches Jirath and starts a conversation. After you hear the signal word, Jirath will turn hostile and you will be able to attack him. Kwalanah will then appear and you can get your reward.