Tentacle gear set
From Diablo Wiki
The most popular of the gear sets debuted at Blizzcon 2010 was the Witch Doctor's tentacle gear set. It's not a set that's a lot crazier than the Witch Doctor's other armor looks, but the fact that it has tentacles that sway and undulate, like some undersea plant, caught the imagination of lots of fans.
It's not known how high level this set is; it doesn't look especially heavy, so probably it's somewhere near the middle of the Witch Doctor's 18 different armor looks. The actual name isn't yet known, nor anything about the stats. It's also not known how much of the set you'd have to wear to get the cool tentacle look going. Just the head and chest piece, or a majority of it, or the entire set. Many questions remain unanswered regarding gear set appearance.
Diablo III artist Trent Kaniuga contributed artwork of this set, that he drew live on stage at Blizzcon 2010. This is sort of "official" fan art; it's not concept art since it was drawn based on the finished game artwork, but since the artist is one of the game's artists... the designation is a bit fuzzy.