I don't know where to begin, this deck of cards is like pure gold. Do you need a way to spice up your encounters so your players fear what goes bump in the night? With these cards you can have your players undergo short, long, or indefinate madness for whatever you personally desire. i recomend having them roll saves against creatures that'd normally have a person fearful, such as; Abberations, powerful undead, seeing demons in their dreams, or other horrifying things. i won't spoil what these cards can do, i read one of them and wanted to stop reading so i'd be just as suprised as my players; but i read them all anyways so i'd be able to write this review.
The art on the back of the cards is great, an old school vector skull that has a slightly shifted image of itself, and surounded by a simple boarder of the lunar cycle that is shared on the front and back. the layout of the cards is simple and easy to understand. Flavor Text, Short Term Madness, Long Term Madness, & the ever important Indefinent Madness. All the effects are fun and flavorful, their are thirty unique cards with three effects each for a grand total of 90 flavors of madness and im frankly supprised how diverse and interesting the implications of the effects are. the Short and Long term madness are very mechanical, things like becoming frightened of X or having to use your action to attack Y, and the Indefinent Madness is usually a more role play oriented thing that the players must abide by, anything from "I love Killing" to "The Dead Suround Me Like Ghostly Shadows"
Overall i highly reccomend this deck of cards, especially if your players are willing to play to the role that the cards induce, i can assure that they will get much use at my table.