I had game against Votann and used Syll'Esske / daemonettes combo against their infantry. I hit 29 times with daemonettes, and then rolled only 5 dev wounds 😂 it was sooo sad :D Syll'Esske didn't do much better. It was just pure bad luck but they Slaanesh is really overcosted. Did You consider simple list with Shalaxi and 3x KoS?