This is the Fool’s Bane HS New Warrior Card coming as part of the new adventure One Night in Karazhan. The adventure is released on the 11th August, not sure which wing this card will be released with but there are 4 wings.
It’s a Warrior weapon and has a mechanic we have not seen before. The card reads: Unlimited attacks each turn. Can’t attack heroes.
With an attack of 3 and durability of 4 this is 12 damage for 5 mana which is pretty decent. Buffing this will be good too, but you will have to keep an eye on how much damage you’re taking. Maybe it will help vs aggo like Zoolock and Aggro Shaman.