There already is counterplay for it.
Bait it. It's cooldown is immense, longer than any skillshot you'd be throwing at him. If he uses it, you basically won the trade, back off and try again while it's down.
Move around it. It only blocks damage from one side and it's pretty tiny before he puts ranks in it. Just strafe to the side and hit him from where it doesn't protect him.
Move away. If you back up, he has to walk through it to keep attacking you, so it no longer provides any protection. Alternatively, just walk through it if he's retreating, and keep up the pressure.
It's an ability you need to play around, with one of the longest non-ultimate cooldowns in the game.