Author here. It’s not a totalizing immobilization, it’s not the same as straight paralysis. It’s more like you’ve forgotten how to move your body than that you physically cannot, it is very difficult to express with just words. Discomfort and pain can help break the spell, as well as an impending sense of danger. That’s not to say it can’t be dangerous, but unless you’re falling into traffic or lava or something, I’ve never felt all that unsafe. Asphyxiation has never been a worry.