This is the Atiesh hs New Card that is equipped from the battlecry activated by playing Medivh, the Guardian.
This weapon is probably the most powerful weapon in the game when used correctly. The 8 mana cost of playing Medivh is expensive, so it’s a late game card most likely to be played in control, spell heavy decks like Priest and Paladin.
Being Medivh and a spell-based activation it’s easy to assume it will go into a Tempo Mage deck but it’s probably too slow for Tempo Mage and you won’t make good use of the effect.