This mission lays out the template for many missions to come. Jump down into the camp and follow your green marker to a Worm- an orc likely to give up the secrets of his scaly brethren.
Sneak up on him and use [E] dominate his mind, as you do.
His thoughts turn out to be exceedingly well organized- select the Palantir-seeking captain to reveal his secrets.
You'll be cutting down an awful lot of these captains as the game progresses, each a little different, and each randomly (for the most part) generated. Learn the stats for yours (though you can always review them later), then ride the kick back up to the real world.
If you want, you can hang around in this portion of the camp and cut down the other orcs- there are other Worms to dominate, but you'll find plenty more later, and there's no loot or XP to speak of. When ready, follow you marker to a motley group of orcs who will serve as your introduction to the bow.
Nothing too revolutionary here- right button to draw the bow, left button to charge it up, and using it expends Focus. Charged headshots are especially lethal, but you can only hold five arrow at a time now, so don't throw away your sword just yet. Instead, cut down the enemy with your bow then gather more ammo via the glowing blue arrowshafts that appear both onscreen and on your minimap.
Investigate the wreckage here, and solve the frequency-detection-like puzzle to reveal the commander's trail.
Follow the trail over a bridge- there's a few orcs and a few ammo caches, so no worries there. Past the bridge Cel will instruct you on using the Wraithworld in a detective-visionish sense to tag your target.
Ignore the other orcs milling around here, and make a beeline for your guy. He should be instructing the troops on a little balcony-patio.
You can scale the wall behind him for an easy stealth hit, but after that the battle is joined. As with any mob fight, it's far more important to counter hits than deal them out. Let the no-names bounce off you harmlessly while you cut down everything that moves. There are no enemy archers in the field here, so between your swordwork and some NPC assistance, you'll have the captain down in no time.
Be sure to loot his body- fallen captains are the best, and nearly the only source of new gear in the game. Note that the loot icon appears where the captain was killed, which may be some distance from where his body winds up.
Snag your new gear, then follow the NPC.
You'll run through a series of plazas, all swarming with orcs. As before, no-name orcs don't give X, so ignore targets of opportunity, and focus on not letting Idril get too far ahead of you. Every so often, you'll need to clear the whole plaza in order to relieve the active (human) sergeant. With so much NPC help this is mostly a matter of backstabbing and button mashing, until the area is secure.
Maintain the pattern until the gates close with a cutscene and a crash. Here you get a primer on summoning your phantasmal glaive- just hold down your attack button until it appears in your hands, then release for a sweeping area attack.
Ending this decidedly minor fight also ends the mission, though your last lesson will be on how to spend skill points- the source of most of your super powers in chapters to come.