The Marks of Chaos
Should a person gain favor with one of the 4 Chaos gods they may be blessed with a mark as proof of being one of their loyal followers. Mind you being their servents comes at a price as every mark bears a downside and can incur the wrath from that gods rival brothers and their followers. Caution to the mortal races that dare choose to accept this power.
The Mark of Slaanesh
When you gain this mark you gain immunity to being charmed, and gain resistance to force damage.
Cons. You may only tell lies (mixing truth with lies is acceptable however). You auto pass the save against zone of truth, You also incur the wrath against the followers of Khorne.
The Mark of Tzeentch
When you gain this mark you gain immunity to being blinded and deafened, and gain resistance to fire damage.
Cons. You gain 2 traits of indefinite madnessthat cannot be cured. You incur the wrath against the followers of Nurgle.
The Mark of Nurgle
When you gain this mark you gain immunity to the poison condition and disease (although you are still a host for it and mauy pass it on to other), and resistance to poison damage.
Cons. Your body begins to rots and puss, and armor that you were rust over time as you become a host for all disease. You also incur the wrath against followers of Tzeentch
The Mark of Khorne
When you gain this mark you caunt as always being under the effects of rage, and when you deal combat damage with a melee weapon you add extra damage as if you where a level 10 barbarian. You also have advantage on all saves versus magical effects and count as proficient when making the save.
Cons. You gain the Bloodfury trait (whenever you see a non-ally you must make a D.C 20 Wisdom saving throw. If you fail the save you must fight the target to the death). You incur the wrath against the followers of Slaanesh.
The Mark of the Everchosen
To obtain the mark of the everchosen is a feat unto its own as you worship chaos undivided (that you worship all the Chaos gods equally). You have managed to gain favor with each of the Chaos gods and have not received the blessings of any of their marks. They then all bless you with the mark of the everchosen and have become their chosen herald of the apocalypse.
When you gain this mark you gain all the benefits of all 4 other marks and none of the cons.