I like the concept, but i don´t think, sinner should create a random sin. Unless you get a lot of Greeds and Novas, you won´t be able to use all your sins. Maybe make the sins standalones and the sinner can combine with one sin, improving its stats or it´s effect?
Also, i don´t like Greed. It´s to cheap, make it cost 2 darkness.
Lust shouldn´t poison. It should delay
Gluttony is too much just a copy of Oty
Well, that's the point. The skill costs are extremely cheap because while they are a tad underpowered atm, they are extremely OP by themselves.
Pride can pwn if used with fodder.
Wrath can be taken advantage of with Rage Potions.
etc.
Anyways, responding to your comments directed at specific cards:
Greed's skill will be changed to 3
because I'm scared of fractals.
Sloth fits the delay better, and I don't want to make cards to similar to each other. Plus, think of it as getting an STD.
Well, what do you want me to put on Gluttony? Destroy? Changed Gluttony's skill to make it OP.