For the Watcher in the Water:
When you face the Watcher in the Water it will lift three tentacles out of the water and swipe at you, Parry (press B)! Then after a second or so approach one of the tentacles and cut it off (press A). The Watcher will appear, shoot an arrow at it (hold L, press A and release A), do these steps 3 - 4 times and you will have defeated him.
Cave Troll in Moria:
After the Fellowship is ambushed by Orcs and you defeat some of them whomever you're playing as will be pursued by the Troll, after giving him several blows your character will jump onto a ledge and be followed by the Troll. Shoot arrows at him and hide behind pillars when he swings his chain at you. Some orcs will be on the ledge as well, defeat them and get posions which increase your health, just keep shooting that Cave Troll and duck behind pillars and you'll get him!
In Amon-Hen:
It takes four arrows to kill Uruk-Hai, whereas with regular Orcs it only takes two |