Board Thread:General Discussion/@comment-24769579-20150301075208/@comment-25733960-20150301223827

That's the easiest explanation: When Regina reversed the Dark Curse in 3x11, Maleficent went back to her human form. When Snow casted the Dark Curse again, Maleficent either escaped the curse, like Hook, used magic to protect herself, like Cora or she was brought back to the cave under the clock tower and she is there in her dragon form, just like in season 1