Instead of the current system of balancing the arrow in the green area it could be random arrow keys coming up on the screen that you have to enter before Vergeance shoots his steamy load. The lower your health is then the more keys you have to press to escape from the grapple. Entering it incorrectly could even speed up the process so players couldn't just spam random keys for an easy escape.
I think I seen that mechanic on another game somewhere. Add on that you have to repeat the entire sequence if you mess up and it sounds solid.
