Merlin - The Eye Of The Phoenix

As a rite of passage, Arthur must undergo a quest alone to prove his suitability to sit on the throne of Camelot.  His quest is to retrieve the Golden Trident from the Castle of The Fisher King.  Morgana immediately seizes the opportunity to get rid of Arthur once and for all.  She gives Arthur a bracelet for good luck, but in truth, it is sapping him of his life and slowly killing him while he wears it.  While Arthur has forbade Merlin to come along, Merlin finds out about the bracelet, finds Gwaine, and together they set out to find Arthur before it is too late.
Of course they find him being attacked and Merlin gets rid of the bracelet allowing Arthur to recover.  When he does, he is not happy that they have saved him as he is supposed to be doing this alone.  Reluctantly, he agrees to them coming along.
In order to cross in to the realm of The Fisher King, they must pass over a bridge that is being blocked by a dwarf named Grettir, played by the wonderful Warwick Davis, who reveals that Arthur is 'Courage', Gwaine is 'Strength' and Merlin is 'Magic'.  In the castle, Merlin is separated from the other two and finds himself with The Fisher King sitting in his throne all these centuries, awaiting Merlin to come.  You see, the quest was Merlin's not Arthur's.  The Fisher King gives Merlin water from the Lake of Avalon that will help him see the way when Camelot's need is darkest.
This was a great episode (I loved The Fisher King) and was indicative of the high quality of writing this show has been developing, especially over this third season.