Ace of spades
You can stick with the standard 52+Joker deck of 4 suits or not. (Not to be practical on you or anything ;-), but I suspect a number close to 52 is easy to shuffle. The 65 cards in Five Crowns is tough! So maybe your characters have larger hands if you decide to have more cards or they have some technique to get around that.)
So, what suits have meaning for your world? Will you use something other than numbers? Do you have a set corresponding to the royals?
From Caffeine for the Creative Mind: 250 Exercises to Wake Up Your Brain by Stefan Mumaw and Wendy Lee Oldfield
Did you know?
The kings in the French decks represent actual kings? King David (spades), Charlemagne or Charles IV (hearts), Julius Ceasar (diamonds), Alexander the Great (clubs). So do the queens and jacks (knaves).
The Ace of Spades picture is usually much larger for a reason? The cards in Europe were taxed and that’s the card chosen for the tax stamp.
That the ace, which used to be the lowest card, trumps the king probably came about during the French Revolution when the peasants revolted against the king?
There’s way more than you thought to question about playing cards :-)
