I'm trying to understand when to use this ability. It genuinely feels like the ability can often be worse than just not using it. It costs a Full Action, and does literally nothing on the turn you use it. It also Immobilises you and stops you from taking Reactions. It genuinely feels like the downsides outweigh the benefits, and you would be less useful in using the ability.
What do people think? I know that Death's Head is strong without the Core Power, but I feel at the very least that a Core Power should not be something that's basically never worth using, or worse to use than not.
My guess is that it can be useful when you're fighting one strong enemy, and you know the fight is gonna be long and that the immobilisation isn't going to be a big problem. But other than that I don't see the use-case.