This would be a reward for beating the deck at gold stake, and would be optional/toggleable.
The intent is to make the deck "more" of what it is, not necessarily harder/easier but leaning more into what the deck is for, and to encourage people to get C+ besides just the achievement.
These are some ideas I have, open to suggestions and changes, but they would be pretty fun i think. These would be additional to the deck's current effect
Red - scoring cards count as discarded
Blue - discarded cards count as scoring
Yellow - start with an additional $10, jokers which directly provide $ cannot appear
Green - earn $1 for every empty consumable slot and joker slot
Magic Deck - +1 consumable slot and start with an additional fool
Nebula Deck - Celestial packs appear twice as often
Ghost Deck - Spectral cards appear twice as often in the shop, spectral packs appear twice as often in the shop.
Abandoned Deck - Face card specific jokers and boss blinds cannot appear
Checkered Deck - Club and Diamond specific jokers cannot appear
Zodiac Deck - start with Tarot Tycoon, Planet Tycoon, and Overstock+
Painted Deck - +1 handsize
Anaglyph Deck - Skipping while you have a double tag doesn't skip the blind, instead giving you a copy of the tag (description is difficult for me to word concisely)
Plasma Deck - shop prices are balanced (everything costs the average of all purchasables in the shop) [credit to Larswjin]
Erratic Deck - starting deck size is randomized (1/2 normal size to 5/4 normal size) and start with 7 to 16 random enhancements in your deck

