This is the final mission in Act I, and it's a long ride, so buckle on in.
You pay a visit on Shelob again, then return to Minas Ithil to act on her vision, again. You arrive just in time to witness the exact doom you meant to avert.
Your first objective is to hold the courtyard. It's a timer event, so do make an effort to take out Ologs, archers, and other fun-spoilers, but don't take too many risks- healing can be a little tricky in the fracas to come.
You also get a bonus for reaching a hitstreak of 20- another reason to keep things casual for now. When the counter does clear, a new wave of invaders will pour in, led by a captain-and-possible-nemesis. Also, the drake will take a more personal interest in the battle.
If Baranor falls, you can revive him by holding down [E]- you can also summon your own bestial or biped allies to this fight. A good basic strategy here is to keep moving- it prevents the drake from getting a clear lock on you, and stops the horde from being able to mass up and pin you into a corner. Whichever strategy you favor, killing the assault leader ends the fight.
Not in your favor though- the city is lost, the retreat sounded, and you catch up with Castamir just in time to watch him doom the world of Men, and get killed for it. Then you get to fight the Nazgul.
This is more a puzzle fight than a real battle. The nazgul are immune to virtually every attack and special attack you have, so don't bother. Their own attacks come in two flavors- one is a teleport stab, which will announce itself with a Counter icon just a fraction of second before it hits. When one attacks this way, the others follow in near instant succession, so do *not* press a counterattack- instead just ready a flurry of deflects.
Their other main attack is a netherworldly Care-Bear Stare that must be dodged with SPACEBAR, though the timing window is much more generous.
As for actually dispatching the blighters, the key is to keep poking away at one until a SPACEBAR counter appears over his head. Use SPACEBAR to roll behind him, stab him in the back, and repeat. When you've dealt enough damage, he'll read as Broken. You can't ride him like caragor, alas, but you can use [E] to banish him from the fight.
Banish them all the same way to enter a series of cutscenes, starting with the ninja-vs-nazgul action the world never knew it needed.
It all ends with you following the elf-ninja back to Shelob's lair. The stones there must all be marked with your footprints.
You'll rush past swarms of baddies fleeing the nazgul, but they're not worth slowing down for. Just follow Eltariel to the lair, and a cutscene in which Galadriel's light should really affect Shelob more than it does. Nonetheless, this sequence of events marks the beginning of Act II, which you'll enter with a new unlocked region, a new power, and a new purpose.
But this quest still isn't done yet. You'll need to test-drive your new domination powers.
Sneak along the parapet, dominating archers. Most are stationary, but make sure you time your mind whammies so the patrolling ones are facing away for long enough. As long as they're the last one in the area, you can use your regular dominate on them if they turn around too suddenly.
When you've made the archers yours, it's time to dominate and or massacre the other orcs in the training plaza below. Once your conversion/kill quota reaches 25, the long fall is finally over.
From this point forward the campaign diverges- you'llhave several different plot paths you can pursue at once. This guide will group them by plot thread, but you can certainly bounce back and forth between them, especially as some will require unlocks you may not alwasy have ready. It's recommended to prioritize the Bruz quests at first, beginning with Ring of Power. This questline will introduce the game's fortress mechanics, and open up the remaining two Mordor territories for travel. After that you may consider pursuing the Gondor quests, which are required to get the Propector skill upgrade, or the Carnan quests, which will grant the drake-summoning Dragonsong skill upgrade.