Scott Epstein from 10th Planet West LA teaches the counter to d’arce. He calls this counter the Mechanic Sweep. As your opponent goes for the darce, you grab his wrist and c-cup his leg and sweep him.
A typical way to get to the d’arce choke is when your opponent is passing your half guard. They usually also get to the d’arce, when they pass your guard, but this counter is specifically when you are have your opponent in your half guard. Ideally, you have the lock down secured.
As your opponent goes for the choke, it’s important to make sure that you pull your head back and you immediately grab your opponents wrist. You want to make sure that they don’t connect their hands together behind your head, because that’s how they secure the d’arce. It becomes a race to see who can do this faster. If you succeed in holding their wrist down, and you can keep your head back, this is when you can go for this sweep.
While you are holding onto your opponents wrist with one hand, your other hand can c-clamp their inner thigh. Then, while you have the lockdown in place, you simultaneously lift up with your feet and with the c-clamp. You then go to your back, and sweep your opponent and end up on top.
This is a fantastic defense to the d’arce that will land you in the top position.