Once you have launched a successful attack upon a target, you may elect to use Death Grip, making that attack continue regardless of what you do. When you do this, you lose the use of this attack mode until the Death Grip is finished.
After each of your victim's actions (except defensive actions), and at the end of each Sequence, you are allowed a Death Grip attack. Your victim can thus avoid some attacks by remaining immobile. This attack works the same way as the original attack did, but automatically hits. The difficulty is the same as for the original attack, any negative outcome is simply subtracted from the damage caused.
To release a Death Grip, you must either give it up (a 1-shot action), or someone else must make an attribute roll, Compare the same attribute the Death Grip itself is based on. So, a Magic-based Death Grip is defeated with competitive Magic rolls, a Strength-based Death Grip with Strength, and so on.