Whoa. 4-mana shades have traditionally been 1/1, like Hoar Shade or suchlike. The only shade with power equal to its CMC was Nantuko Shade, a tournament-level rare. This probably isn't as good as that, but still looks very good for a common.

If this existed in most Magic sets, it would warp half the table into going mono-black. I remember how that used to operate in Urza's Saga, where both Pestilence and Corrupt were printed at common. You only needed two of them, and the rest of your deck could be terrible. This card = same thing. Play on round 4, swing on round 5, 6, 7 and force your opponent to keep chump blocking. Could be fine at uncommon, I supppose...

Still a potential bomb, but most chump blocking kills it.

Ah yes, sensible change. Now it's still scary, but the controller needs to kill all your blockers.

One problem: this is now a red card with a red ability.