Do you have any hints on how to access the fortress in the savannah? I've explored the swamp a fair bunch and I'm still not sure what I'm supposed to do, and I might be missing something.
You need to complete the questline in the swamp. That means finding the flimsy shears blueprints in the serpentfolks' lair, discovering a corrupted dungeon within the south-west depths of the swamp, and doing renown tasks for the new faction you ally yourself with afterwards.
