I don’t see Rumpelstiltskin giving people power–he wants to be the one on top, unless he was able to predict how Cora would have Regina, who would become a very useful tool. But then how would he have given her power? With gaining power in this show, it seems that killing someone is the only route to take. He may have told Cora about a powerful wizard or wielder of magic, and told her how to kill them.
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