Shelob's Knife in the Dark and Rain of Arrows are two missions as part of the Shelob storyline in Middle-earth: Shadow of War.
These unlock one after another, and come after completing No Man's Land, The Arena, and Before Dawn quests from the earlier Gondor storyline.
If you are interested in completing other missions in the game, our Shadow of War guide and walkthrough can help.
Knife in the Dark
Reward: 2100 XP, 360 Mirian
Bonus objective: 300 Mirian
Defeat the Olog-hai: There are a few approaches here, but we'd suggest taking a defensive stance as a head-on fight is unlikely to go your way.
Dodge his attacks when prompted which will send you sliding through his legs enabling you to get in a few hits from the rear; hitting a well-timed Stun will then enable you to climb on his back and perforate him by mashing attack.
Follow Gollum: You shouldn't encounter any trouble if you stick close to him, but it's still worth keeping an eye out for wandering Orcs.
Defeat the Uruks: A pretty straightforward fight.
Follow Gollum. Find the Assassin's Victim: Use Wraith mode to reveal a set of footprints to follow.
Follow Gollum/Find the Assassin's Victim: There are a few Orcs near the next victim that you'll need to deal with first.
Follow Gollum/Defeat the Patrol/Follow Gollum: Another Olog-hai to deal with, and a few standard Orcs - if you mount the Olog-hai you can use him to smash the others while you're stabbing him.
Find/Interrogate the Assassin's Victim. Reach the Assassin: Head towards the marker, and once your target is in sight shoot the Morgai Fly nest above his head to clear the bonus objective.
Defeat the Assassin: Watch out for his unblockable attack - it can take off half your health in one swipe, so dodge out of the way when prompted to avoid its poisoning effects. Beyond that he doesn't have any real tricks up his sleeve.
Rain of Arrows
Reward: 3300 XP, 380 Mirian
Bonus objective: 300 Mirian
Need more help? Our Shadow of War guide and walkthrough gives you an overview of everything you need, but if you need something in particular, we have pages on Shadow of War Fortress Sieges, how to earn Mirian in Shadow of War, a guide for how to import your Nemesis and Follower to Shadow of War, collectibles guides like how to get all Shadow of War Legendary Armour and Weapons sets, a list of Lost Artifacts and Web of Fate locations, and Ithildin Door poem solutions and Shadows of the Past, along with how to grind XP in Shadow of War to power through the tricky Shadow Wars endgame and get the true ending. Finally, there's Shadow of War's army building explained and the best skills and how to earn Skill Points.
Reach Baranor: Head to the marker.
Defeat Archers without Raising the Alarm: Use stealth to creep around the outside of the camp and take out the archers - there's plenty of cover, and most of the Orcs are minding their own business so meeting the optional objective of killing four with stealth is easily done.
Reach the Vantage Point without Raising the Alarm / Summon the Gondorians: With the archers out of commission this is easily done.
Defeat the Warchief: with assistance from the Gondorians and their flaming arrows you shouldn't need to worry too much about the little guys, so focus on your quarry.