So you know when you get a deck of cards and it comes with a little bonus card explaining how to play poker or smth? Yea that.
Rules cards are a new type of consumable that focus entirely on deckfixing, mostly via changing cards' rank and suit. They can be found in Instruction packs which work similarly to spectral packs (Normal has 2 with 1 pick, Mega has 4 with 2 picks). They're also all based on classic playing card games so that's fun.
Go Fish
Converts 2 selected cards of the same rank into the most common rank in your full deck (Currently: [Rank])
Solitaire
Changes suit and decreases rank of 2 selected cards by 1 (Spades/Clubs <--> Hearts/Diamonds)
Texas Hold 'Em
Converts 2 selected face cards into Aces
Rummy
Converts 4 selected cards into ranks descending from the leftmost card selected
War
Converts 2 selected cards into a random higher rank held in hand
Spoons
Converts up to 4 selected cards into the rank of a random selected card
Kings Corner
Creates a King of the selected card’s suit
Old Maid
Destroys 1 selected face card, converts 2 random cards in hand into Queens
Blackjack
Select up to 3 cards, convert selected cards into Jacks if sum of selected cards ranks equals 21
52 Card Pickup
Select 1 card, creates 4 playing cards that match its rank or suit
Presidents
Select any cards of the same rank, destroys all selected cards
Crazy Eights
Converts 4 selected cards into a random other suit
Also a pair of vouchers cause I feel like it
Manual - Base
Rules Cards can appear in the shop
Strategy Guide - Upgraded
Rules Cards can affect 1 additional card