Sometimes, the players may seem to have meta knowledge of an adventure. The GM can openly display the cards in the game, or hide them, dependending on play style. For The Cleaves, it's another deck to draw from each new room. Any previous rules that conflict are discarded.
For a normal game, one or more players admit they were exposed to spoilers, or not. The GM can roll for a rule change card an play the whole module that way. To make the players feel more included, each may draw a card and hand it to the GM without looking at it. The GM applies all the cards.
1: Flip the script The good NPCs are really bad, and the monsters have reformed. Items become cursed items, while cursed items become non cursed.
2: Positive energy leak Everybody and everything heals one point a round. Undead without special resistance will take the damage.
3: Negative energy leak Everybody and everything takes one point a round. Undead will heal the damage.
More on 1: Illusions are replaced with real and real stuff is replaced by illusions. An illusionary wall is replaced with a wall with a secret door in it.
4: Goofy Gas Use tic tacs to represent illusionary weasels, or a clear dice box to represent the big, pink, elephant. While these things cannot touch them, they can provide cover. Anyone who fails their 15DC will save must interact with the delusions.
5: F/MU rebalanceTrue strike, shocking grasp, magic weapon, and other combat spells can only be passed on to fighters(including monks) when cast. Thus the wizard can touch the ranger's bow giving them true strike for their next shot.
6:Bad Luck AEveryone roll an intelligence check vs 18 or they left something back at their last campsite or homebase.
7:Spider AttackIf characters are not sufficiently challenged, a giant spider attacks from above. The higher level the characters, the bigger the spider.
OK, so what does 'Cleaves' refer to anyway?
A random space dungeon me and yellow dingo started and many users contributed to. There is a deck of rooms, monsters, treasures, and plot hooks.
Look here.
https://paizo.com/threads/rzs2lcsk?What-does-cleaves-mean#1