When Icela attacks a dreamer's mind with the Momok's lasso, she can hold onto his mind after he wakes, keeping it under her control. So even though the dreamer is now awake, he is still having his nightmare. He cannot tell if the things he is seeing are from his nightmare or in the real world; to him they are all real. People around him can tell that he is "not himself". He is Dreamwalking!
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