So I have recently been toying with making a Slaanesh themed force for Chaos, and thinking through the themes I want to put up one was fear. So looking through the Chaos codex I noticed we do have quite a few way to lower people's Leadership through tools such as these.
1. Night Lords, obvious as each unit up to a max of 3 gives a -1 modifier to enemies within 6 inches.
2. -1 Leadership to any unit within 1 inch of a raptor unit.
3. -1 Leadership to any unit within 1 inch of a Chaos Spawn unit.
4. -1 Leadership to any unit within 6 inches of a unit with an Icon of Despair
5. Warlord Trait Master of Fear which makes people roll two dice and take the highest while around your warlord.
So a Raptor unit with an Icon of Fear would give anyone within 1 inch of them a -3 Modifier, toss in a Chaos Spawn unit close too and that'd be a -5. I wouldn't be too bothered myself to make the force Night Lords and give them the Mark of Nurgle, I rather feel I want to paint them Slaanesh and play them as how I envision Slaanesh forces.
Would this sort of leadership damaging playstyle be at all viable you think? The goal being to get just a few guys down and then low leadership rolls doing a lot of the legwork. I mean a raptor unit in an of itself isn't bad at all.
An optional idea for me would be a Patrol Deatchment of Slaanesh Daemons to get access to the Slaanesh Psyhic Powers, one being a simple -1 leadership to a unit and the other roll 2d6 and the unit take as many wounds as you go over their leadership.