I liked the idea of an old style Black Legion army containing some of each of the cult forces but painted in BL colours with the cult shoulder pads painted in god specific colours.

Below is a 1500 point and an upgrade to the 2000 point list.

1500 Black Legion
HQ
: Daemon Prince, mark of Slaneesh, Lash of Submission. 135

Elites: 5 Terminators, 1 CF, 1 PF, 1 Hvy Flamer, IoCG, 2 Combi Melta. 200

Troops: 7 Plague Marines, Champ with power fist, 2 Plasma guns. 231
Troops: 9 Thousand Sons, Sorceror with doombolt. 254
Troops: 8 Berserkers, Champ with power weapon, Rhino. 233
Troops: 6 Noise Marines with Sonic blasters. 150

Heavy: 2 Obliterators. 150
Heavy: Vindicator, Daemonic Possession. 145

Total 1498

2000 Points

Troops: 10 CSM, Champ with power fist, IoCG, 2 Melta guns, Rhino Havoc Launcher. 270
Troops: 10 CSM, Champ with power fist, IoCG, 2 Plasma guns. 230

Total 1998