Acheron Class Heavy Cruiser

Third option for a Battlecruiser slot in a Chaos Fleet, Acheron Class retains spinal weapons of Styx and Hades (two lance turrets, macrocannon turret, missile pod turret), but its primary weapon is more fitting to Chaos - four lance decks. That means that it has ten lances overall.
Ironically, fluff claims only one Acheron Class was built, and it hat three lance turrets and different broadside guns: http://wh40k.lexicanum.com/wiki/Acheron_Heavy_Cruiser.