What are everyone's thoughts on:
Coupon Cutter; Shop items are half price. This seems like a simple -- although potentially OP -- very sacrifice room style item. I'm not actually sure if this is possible in the code immediately, but if not it seems fairly straightforward to implement (for Keith!).
Conservation of Mass; +10 max health, health items no longer spawn. Making it so that health items no longer spawn is interesting. Possibly more of an incredibility style item, though. How about, health no longer spawns but you regenerate 1 per room.
Ptarth is starting strong with so many good ideas.
Coupon cutter is the main one that caught my attention. I'd pick it up in 3 runs out of 5. Though I would recommend reducing the discount to something like 33%, which is already very good with all the costly purchases you can make in a single run.
Conservation of Mass is kinda weird. It's like those powers in other games that prevents you from healing with regular items but give you vampire-style lifestealing, only in this case the vampire power is sold separately. I don't know what, but I think an alternate way to heal should be included with it. Wait, what if the player could regen health using money (3-5c per hp)...outside of combat only? Meh, sounds like a nightmare to balance.
Bouncy Balls, as it is, sounds like a super fun incredibility. If changed to affect only the player, I could see that as an interesting sacrifice item. (I'd love to see Wind try it if it's made as an incredibility)
Adrenalin - Power in exchange for losing health is interesting I think. How about instead of every 10 seconds it would be when you enter a new room? That way the player can calculate the risk/reward at any given time and offset the downside with proper planning. If it makes a player think more, I consider that as a positive thing.
The double/halved for everyone powers, I don't think would work well because of all the pattern based attacks that couldn't follow the change in pace. Make battle too fast and many patterns don't have time to do their thing. Make it too slow and attrition-style patterns become overly dangerously.
I don't understand the reflect and the sticky shot powers, could someone explain how those would act?