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We are having a discussion on our FLGS forums and are so far unable to come to a conclusion, so I thought I would ask a bunch of WoC players..
Lets say the marks are not clearly emblazonned on the unit, maybe you didn't take a banner, or maybe you decided to choose a paint scheme that is out side the box (which is what I did) but you did indeed give them a mark.
Are you obligated to tell your opponent what marks each unit has?
What are you obligated to clarify to your opponent, everything but magic items?
If my opponent asked what had what mark, i would feel like I had to tell them, which isn't a big deal, I would love to get the jump on someone though.
I usually announce what mark my units have as I deploy them and if an opponents asks I am happy to repeat it.
I think of it as the following, marks are not magic items and are simply unit options. So would you not tell your opponent that your unit of warriors has shield, halberd and command?
Along those lines though, don't you have to have them modelled to represent the halberd/shields so on.. so do Marks of Chaos fall under the same curtain?
I play ever evolving armies, my lists are never the same twice, and I certainly don't want to be roped into buying 100 warriors or 200 marauders because I need so many "marked' as Khorne/Slaanesh/Tzeentch/Nurgle/Unmarked..
model them however you want. I always tell my opponent what everyone has and is marked with before I start the game. If it's confusing, write it on a piece of paper and put it ontop of the unit. There is no WYSIWYG in any of the games I play, its more "WYSIW I tell you it is" I refuse to have the rules ruin my fun with modelling. Modelling/Paintin is probably 70+% of the fun I get out of this hobby.
once suggestion I saw that sounds like a good idea was making your movement trays represent the marks. this way you can switch every game and still clearly show what you have.
If you look on Games workshops home page under 40 k and Bitz, Miscellaneous that u can buy cheap Icons to Chaos to Attatsch to the banner or somthing it's a good idea and u can easy switch them just place a pice of tape on the backside.
What one of my friends does is simply have a load of standard bearers for each mark, allows things to be very clear at a low cost
Current painting project: 2300 pts of Dwarfs in 5 weeks.
In previous editions of the Chaos book, it stated that marks took many forms, sometimes something easily hidden, othertimes a great mutation. In the current fluff, they mix&match alot of stuff between the gods, either by apeasing multiple gods or by taking trophies from fallen rivals.
This being the case, I don't think you need to model them according to mark.[ No where does it say that Nurgal champions ONLY wear green ect. As far as what is considered proper when announcing to opponents, that is up to your playstyle. Sometimes I like to keep my hand to myself, while other times I want to tell my opponent everything so I can smite him on an even level.