afro-slav said:
But how can one not if the creature is unable to take any actions?
I would think the same.
I think the victim could be allowed a new saving throw each time he is threatened. If he fails, he is attacked as if flat footed. After he is attacked, another save will be in order. You could grant a cumulative +1 bonus to his saving throw each time he has to make a check.
You could consider the effect of the spell on the victim as if charmed, he is bewildered, his mind is somewhere else. He could be aware of things, but he is dettached, as in dream where someone is talking to you, but you can't listen, and you don't care. Or you could consider the victim under the overpowering gaze of the sorcerer. The sorcerer is preventing him from acting by shear power of will.
Remembering Hyboria's Fiercest, where you can push physical abilities to the extreme, maybe a similar rule could be applied to saving throw checks to escape entrancement.