The rarity of Ancient Crown of the Arachnarok is Rare. At this moment the item is available for trade.
Ancient Crown of the Arachnarok is a skin for Broodmother. The skin was added to the game on August 31, 2016, it was created by Anuxi.
Ancient Crown of the Arachnarok has been recently added to the game, which makes it rather popular with the game community.