Hey, I love Warcraft III, most fun RTS there is to me, the hero mechanic is really interesting and adds a lot of depths to the game on top of units variety.
I loved what Blizzard pulled out with Co-op missions and commander in Starcraft II. And I thought to myself it would be awesome to see a co-op happening as well on War III: Reforged. With heroes at the reign of customs armies,
Therefore this is my suggestion: Add Co-op to War III: Reforged!