I just had a moment of sudden clarity. Having been such a big fan of Warhammer Chaos for so many years I have no idea how I never realized this before. Perhaps everyone else allready realized this and I was just being slow:

Look at the symbol of Tzeentch:

http://static.giantbomb.com/uploads/scale_super/1/17172/934501-tzeentch_mark.png

In a lot of versions of that symbol, it looks like a disc with a waning moon behind it. The waning moon being more or less twisted.

This is actually the two moons of the Warhammer world. The disc is a full Morrslieb with a waning Mannslieb behind it. The twisting powers of the full chaos moon distorting Mannslieb on Geheimnisnacht (the one night of the year when Morrslieb is full and closest to the world and the night where sorcerors of Tzeentch are at their most powerfull).

I'm sorry, this might not be interesting to many others but I just love suddenly discovering new tidbits of the setting that I have missed until now. Warhammer is a setting that just keeps on giving

I thought it looked more like the eye of a bird of prey, looking at its next victim, you. er me.

Yeah, some of them have more of a birds eye look, which might be why Tzeentch is associated with birds. But I seem to remember that particularly the older publications of Warhammer stuff had a distinct waning moon look.

Never thought about that, interesting. I had to search for more pictures.

The "moon-look" is more obvious in this:

http://z.enha.kr/pds/3/36/m1570123_40K_daemons_GS_Extra_Image_Tzeentchh.jpg

or: http://fc09.deviantart.net/fs45/f/2009/058/a/f/Mark_of_Tzeentch_by_Duet.jpg

or: http://img.photobucket.com/albums/v310/beestieboy/tzeentch.bmp

Yeah, that's what I seemed to remember. The older versions of the symbol had a more apparent moon-like appearance. I remember wondering what the symbol meant when I was younger and got into Warhammer (via fantasy battles). THe other symbols were mostly easy to interpret, but not that one. And it turned out to probably be the most clever one

I made a quick mockup in photoshop of what a Gehemnisnacht moon might look like when Morrslieb drifts in front of a waning Mannslieb.

Wow, it's like its been hiding in plain sight all these years, nice one. Thanks for the Gehemnisnacht moon picture too, I'll be sure to use that soon.

Now if you can just knock up a quick 'Morrsleib eclipsing the Sun' photo for the conclusion of the 'The Dying of the Light' campaign, that would be tip-top! Shy bairns don't get sweets, as we say! ;-)

I googled some pictures of solar eclipses and you can not really see any features of the moon during the eclipse, as the side of the moon facing the earth is in complete shadow (naturally, since it has the sun right behind it).

However, I ran into this picture of an eclipse that I thought was pretty fitting for a bit of a mystical feel to the eclipse: http://solar-center.stanford.edu/images/vojto1_pub_eclipse.jpg

I threw some quick filters on it to make it darker and greener:

You are a true gentleman, Tzeentch would be proud to create a spectacle such as that!

Cheers!

You're welcome

And since I was already messing around in PS I made a slightly better version of the Geheimnisnacht picture. Someone with some actual skills in photoshop could probably do much better though. It has been way too long since I used it.