The Forbidden Lands is a relatively small area, and offers little in the way of unique enemies or rewards, with the exception of the loot from a couple of optional field bosses. However, the Forbidden Lands are still important, as they serve to connect Leyndell, Royal Capital with the Mountaintops of the Giants — while the bosses here may be optional, traversing the Forbidden Lands is not.
After taking the elevator from the end of the royal capital, you’ll be able to exit the building and go down some stairs — on your left is the Forbidden Lands site of grace. If you want to fight the Night’s Cavalry that’s a little bit up the road, wait until night at the site of grace. Then, from the site of grace, head east into the fog.
There’s a ton of fog here, and it can be easy to get turned around. If you’re ever confused about which way to go, just open your map — despite not having the map fragment for this area, you’ll be able to see the outline of a road. The way forward runs southwest to northeast, so go northeast on the road (just like this) whenever you’re in doubt about which way is forward.
The path (such that it is) will curve northeast. Look for bloodstains on the ground, as you’ll likely see them soon — these indicate nearby some vulgar militia that will ambush you from behind the trees. They’re pretty weak, but have a new ranged attack that can cause you problems even while mounted, so don’t underestimate them. Past this first group of enemies, look to the east (you may have to ride a bit further down the path) for a large broken piece of arch — it’s got a few militiamen on it, and at its northern tip is a Golden Rune .
Now head back onto the path and continue northeast. The way forward should narrow, with a large tree sitting in the path. To the left up against the rocks you’ll see some Nascent Butterflies, but watch out for the poison traps that protect them. Continue northeast through the trees and — assuming it’s still night — you’ll soon encounter a Night’s Cavalry, and in your road. This fan of black attire drops the Ash of War: Phantom Slash. The strategy in the guide below will work just fine, although the trees and narrow nature of the terrain can make it tricky to line up good approaches.
With the cavalryman dispatched, continue following the road northeast. It will curve slightly to the right and narrow considerably — when this happens, start riding slowly, as you’ll soon come to a small gap you need to jump across. After the first jump, you’ll traverse a small rock outcropping and then need to make another jump eastward. On the other side wait a few more vulgar milita, two nearby and one further to the east. Resist the urge to fight them near the edge of the cliff and get safely away from the drop before engaging.
Continue northeast, and you’ll soon see a crimson tear loot beetle in the road — three vulgar militia are hiding nearby: one just to the right behind the rocks, one further up the path on the left, and a final one behind the next set of rocks on the right. Beyond them, the way forward becomes steeper, and curves slightly right. If you’re a mage and need more cerulean tears, there is a loot beetle on the edge of the cliff north of the path here.
Look to your right as you continue uphill, and you’ll see a large skull. Head over to it and snag the Somber Smithing Stone  from its jaw, then go back to the path and keep heading northeast.
You should almost immediately come across an illusory tree (it’s hard to miss, since it’s the only thing that isn’t white or black), where you’ll find a Golden Seed, and just to the west of the tree are some more Nascent Butterflies flapping above another broken arch. Keep going northeast up the hill, and you’ll find a couple more flask beetles. There’s a militaman off to the left here, but he’s too far away to aggro unless you drift off the path. The path curves north and you’ll see some statues flanking a staircase — as you approach the stairs, a Black Blade Kindred will show up to block your path. Fortuantely, he actually doesn’t prevent you from continuing forward, so you can (and should) ignore him for now.
If you’ve been following Millicent’s questline, her summon sign should appear just north of the nearby Stake of Marika, which is on the right side of the path just before the stairs come into view — she can be useful in defeating the Black Kindred Blade.
Before going up the stairs (assuming you’re confident in your ability to stay away from the boss for a few extra seconds), go left around the stairs to grab the Freezing Grease from the base of the tree. Then go back the staircase and take them all the way up — at the top of the stairs you’ll find the Grand Lift of Rold, and on your right will itssite of grace. Once you grab the grace and rest, you can go back down the stairs and face the Black Kindred Blade if you like — it drops the Gargoyle’s Black Axe, Gargoyle’s Black Blades, and a respectable 60,000.
Once you’re ready to move on, head all the way up the stairs that lead to the Grand Lift of Rold, and continue onto the lift. By standing in the circle just before the statues, you’ll be able to press your interaction button to “Hoist medallion” — this will activate the lift and take you to the Mountaintops of the Giants! If you haven’t yet recieved the Rold Medallion from Melina, you won’t be able to progress to the Mountaintops of Giants. You’ll need to go back to Leyndell, Royal Capital and follow the steps in Part 5 that allow you to recieve the medallion.