Board Thread:Spoilers!/@comment-34657163-20180314004535/@comment-34657163-20180315191540

Bottondoro wrote: It's the dark curse or it's a different curse? If as I assume and Drizella herself told us, Regina tought her how to have her revenge, it is the dark curse. So the most important ingredient is the sacrifice of the one you love most. You can't use the same victim of the sacrifice two times (Regina's father is dead...) how can it be a sacrifice if you 've already lost it? So, if as the witch of he coven say, they need the lady and most important ingredient, that is sacrifice. Whom Regina loves most? Henry.... Except, the episode specifically explains, "ingredients...I have seven of them...the eighth one, and of course the hardest to find, magic from a witch who crushed the heart of the one they love most".

I'm assuming it's supposed to be the dark curse, but it's obviously been retconned and instead had the power of eight witches (granted it was implied in the third season groups of witches could do powerful things), the eighth of witch having crushed the heart of the one they love most.