What color of wax effigy should one use for cursing an enemy? I’m assuming black or red…
Black
Whatever you want really, for the most part color only holds importance to the person creating the figure. If a certain color gives you more of a connection use that. You could use mauve/tan/brown candles to make the wax match their skin color or even use the colors attributed to their zodiac sign similar to Bucklands astral candle concept.
I’d try to add as many personal links as possible to the figure, hair, handwriting, photos, D.O.B. etc, they can be burned to ash then added to the wax while it is melted.