The Boomsday Project Guide
For the rest of the game,your Hero Power can target minions.
Never seen this Card in Play, is it really so bad or is it underrated?
It's an arena-only spell that will appear as an option during the draft for a limited time.
From Hearthstone Wiki:
Deadeye is unique to the Arena and can only be obtained via drafting it during an Arena game.
Deadeye is uncraftable and cannot be crafted or be obtained from card packs.