As nice as it would be to have a full set of Myrosian, the Helm does not exist...yet
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The Legion Leggings however, do exist, and can be found in the Mercian Royal Crypt. I'm pretty sure I found them in the farthest-side sarcophagi. So you have to prove yourself by making it all the way around...or you can skip the other rooms to get there
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Using Ruby Keys and defeating them bosses can net you some yummy rewards. Surviving the initial wraith ambush to enter the Crypt...best of luck surviving there~