Board Thread:Wiki-Related Discussion/@comment-1916997-20171222202521/@comment-6302057-20171228072312

In my personal opinion,

Caster: Drizella and the Coven Only Ingredients: The eight Coven members' combined magic, plus Regina's blood

This current curse is Drizella's as it fulfilled her desires, and she had help casting it from the Coven. Regina did not cast it, merely her blood was used as the final ingredient to activate the curse, much like a crushed heart was the final ingredient of the original Dark Curses.

Note that in this instance, activate does not equal caster.