I am well aware that I'm by far not the first person to suggest negative playing cards. I'm just mainly suggesting a spectral card for it. I've seen people say they could allow for a larger played hand but that's way too complicated imo. I think it would just be an effective +1 (or more) hand size while in hand. And the way to get it would be either A: a new spectral card, or B: a very rare chance in standard packs.
New spectral card: Haunting
Adds 3 random, otherwise unenhanceed negative cards to deck