BBC Merlin but the reason Arthur gets called once and future king is because he and Merlin are two sides of same coin and he is the "once" part while Merlin is the "future" part. You can't see a coin's two sides at same time. That's why Arthur "the past" needed to die for a better future (aka Merlin to be immortal and magic to be free because Arthur and his ways were stuck in past)
So he wont actually get resurracted because when Albion is in need; Merlin, the future side of the coin will deal with it and that's why he is immortal.
Does it makes sense ?
















