Guys do you have any tips or ideas about how to use >Marks of Chaos Gods< cards? Do you give them to players or only to NPCs? How does it influence your games? All input appreciated.

They are genereally designed for NPCs but should work fine for PCs as well. However, it should NOT be easy to get as it is a distinguisihing mark as a champion of the god.

I have been running a chaos campaign for over three years and the character who has survived all the way until now just doubble-crossed the leaders of a slaaneshi city and massacred them in a ballroom during an orgy. That was a big enough accomplishment for Tzeentch to bestow his mark upon him.

If you give them to your players just for fun, then that's pretty cruel as a GM because those marks should be the mark of doom unless you're running a Chaos Campaign.

I mean you could certainly write an interesting story where they wake up each bearing one of the marks, but unless you're a truly horrible person you should have an adventure in mind for your players to lose said marks.

I've done both, and it has worked well.

As an example I once had a group of beastmen with Mark of Nurgle as villians in a story. When the PCs finally found them, that combat encounter became a really horrific and a few of the PCs got really sick. Another campaign a PC Wizard got the Mark of Tzeentch after a string of particularily bad choices. The campaign was drawing close to an end and he had a few mutations allready so he ended up beeing a really horrible chaos sorcerer.

Both worked well, but as stated above, if a PC gets the mark he/she is pretty much doomed, so you should have a plan for it if handing it out. NPCs is easier, there I usually use the chaos mark to flavour the encounter. I don't do it too often, I want encounters with chaos marked bad guys to be memorable.