I'm honestly curious about your opinion about slaanesh baing a bad figure to have in grimdark 40k. Since i don't want to derail the thread, i'd love to receive a PM with your ideas on the matter
Just out of sheer curiosity, since, you know, slaanesh is my preferred god!!
(even in Real life
About a valid sobstitute...well, malal ,imo, is on junior league, i've never seen him as something more than a nuisance to the true gods (even with the old comics badassery: that was just 1 champion...maybe the only one he had. I would love to see him pitted against Doombreed and see who's best at killing stuff.)
A god to replace slaanesh could only be a sobstitute. We could take a god of ignorance and zealotry, wich are widespread in the galaxy. We could expand from this and include the general concept of malal, getting to a god of entropy, obscurantism, self destruction and ignorance; something like a god of Darkness: the void in space, the oblivion, the non-existence.
I am picturing it like a mixture of the Neverending Story's "The Nothing", the Goddess "Shar" from Forgotten Realms 2nd edition and the warp-manifestation of the dark-ages on a galactic scale, all sprinkled with Malal's deuchbaggery.
And we could call it "Nihil, the Empty God, Lord of the Void"
Clearly a god fiercely opposed to all the remaining three (expecially with Nurgle due to his claim over entropy...)