CURATOR COMMENT
-Fix the discrepancies between the Text in the table and the card (For Wretch, the card image need to reflect the table's correct text)
-Provide a link or source of artwork that isn't your own (Or specifically, you should cite Wretch's art as being done by redium; if the others are done by you, you can leave that part blank)
Excluding those mistakes, the variances in 'Sins' are decent. (I suppose I personally embody Sloth in both element and in real life XD). I feel that Sinner | Wretch could be the 'rare' cards for Darkness, assuming the cost of Sinner | Wretch is decreased, while the ATK|HP values of some of the other sins (mainly Sloth, Wrath, Greed, and maybe Lust) increase. As you said - this would probably work best in a Darkness-based rainbow, but it'd be a fun card to use.