Diablo III: Reaper of Souls

We just need Blizzard to introduce Runewords to D3.

I think people underestimate how complex and shitty the runeword system was. There were literally billions of possibilities, and at one point, some where unknown. The rarity of anything above Gul makes Legendaries in RoS look like blues.

I think maybe adding a few more sockets to different slots and having Legendary and Set gems would suffice. They'd perform identically to what a runeword implementation would, without the added complexity of combining complex or large sets and adding large number of sockets.