User blog comment:Ḡwẵine Ḹٍٍkƨ Ĺiĸe Ͼềлȑềd/Arthur versus Mordred/@comment-4135736-20120514121335

That was a really cool battle and this is how I imagine that duel to happen in this show:

Merlin does an enchantment to disable Mordred's magic, exactly what he did to Morgana, to prevent Mordred from harming Arthur with his magic. Merlin (who is now an old man) is then, however, distracted by Morgana who engages him in a fierce magical duel while Arthur and Mordred confront each other. Mordred attempts to kill Arthur with his magic but Merlin's enchantment prevents that from happening, making him attack Arthur with his sword instead.

At the same time when Merlin and Morgana are fighting, Arthur and Mordred engage in a fierce sword fight until they both knock each other to the ground. Then Arthur and Mordred both get up, grab their swords and stab each other at the same time, they both fall to the ground. Merlin and Morgana stop fighting when seeing this and while Morgana goes to Mordred who dies in her arms, Merlin goes to Arthur who then dies after seeing his best friend for the last time.

Merlin then cradles Arthur's body, grief-stricken at the loss of his friend, but hears someone else crying at the same time as him. Merlin then discovers to his shock that it is Morgana crying, apparently regretting her actions. Merlin then attacks Morgana with his magic, ignoring her grief, causing her to fall to the ground (which is where her vision of Emrys takes place, ending with her sacrificing her life in Avalon to ressurect Arthur).