>>22971202
All the chaos gods have a degree of overlap. The Slaaneshi sadist who gets off on inflicting pain and misery could be considered, from a certain point of view, to be empowering Khorne slightly by their taking joy in bloodshed. The sorcerer of Tzeentch who spends decades perfecting his master plan is indirectly empowering Slaanesh though his obsessive perfectionism. The berserker who reaches insane heights of rage is feeling an extreme of emotion, which could be considered to fall under Slaanesh's purview. Nurgle's worshipers experience change before they reach stagnation, and the love he bears for his followers also falls slightly under Slaanesh's domain. Slaanesh, meanwhile, inspires almost as much change as Tzeentch does, as gifts and mutations are given, experimented with, warped and used for every possible experience, and destroyed once they become boring to make room for the next.
It's foolish to say that each god's purview belongs to them and them alone, since Chaos at its base is raw emotion, and no emotion is ever so precise. But despite that, it's also foolish to claim that one god or another is more powerful then the others because "their domain covers everything", since that street goes both ways.
In the end, what really matters is the mindset behind the action. Killing for the sake of killing serves Khorne, killing for the joy of causing pain serves Slaanesh, killing to move forward a plot decades in the making serves Tzeentch, killing for the sake of stillness and stagnation serves Nurgle, and all of the above can serve anyone if it's dedicated to them.