Cannot go back to Act 3 Cruel Difficulty Ziggurat Encampment

Hi, after I finished the campaign the cruel diff act 3 ziggurat encampment portal seems to be closed now and there's no way for me to go back to the encampment unless I'm missing something here. I killed Ignagduk, The Bog Witch but I forgot to talk to Sarvi to get the reward and no there's no way going back to where she is, This might be a problem with any quests that were not completed before finishing the campaign since you can't go back to talk to anyone.

+ bump

You can go back to it by accessing it through sandswept marsh.

Go to the Drowned City (Present) - right near the checkpoint there is an entrance to Ziggurat Encampment.
This way you may finish the quest.
I had exactly the same issue.