Let me help you. Where you stand must be middle. You are killing the orcs randomly but beware that Legoas, Gimli, Aragorn, Gandalf must live during fighting against orcs. There are some huge orcs will come to kill your friends. You can kill it with the spears in one or two shots. When that goes down quickly run toward left to defeat another huge orc.
Come to the middle again and make sure your friends well. Respectively kill the rest of 4 huge orcs. Not to the little orcs the ones with mace I meant. And nazguls will show up afterwards if you can achieve to get through the next part. All you need for killing nazguls throw the spears into them and attack the one you threw till it dies. Then you are finally ended the episode.
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Will be going to London on March of the 30th