This shape is not three rules bolted together; each covers a hole the others leave.
Iconoclast Fiefdom supplies the bodies. A Chaos Knights army without allies is three or four models and cannot contest three objectives. Up to 500 points of DAMNED infantry fixes that, and its Dark Sacrifice stratagem moves D3 plus 3 wounds from a cheap unit to an expensive one every Command phase, which is the best exchange rate in the faction. Remember the exclusion: Accursed Cultists cannot be the donor.
Bastions of Tyranny supplies the damage, provided you own a Knight Tyrant. Its rule needs battle-shocked targets, and the army rule is the machine that produces them: Deathly Terror and Despair each worsen Leadership by 1 within 9 inches and stack, and Dismay forces tests on units below Starting Strength.
Hunting Warpack supplies the reach and the cheap scoring. War Dogs spot, and its Leash of the Masters stratagem lets a War Dog shoot and then start an action, which is how secondaries get scored by models you can afford to lose.
The obvious caution. Two of the three are narrow. Bastions of Tyranny does nothing without a Knight Tyrant, the only datasheet with that keyword. Hunting Warpack's two enhancements are HUNTSMAN only and EXECUTIONER only, so if your War Dogs are Brigands and Karnivores its whole enhancement budget is unusable. Check both against your actual collection before committing.
The alternative if durability matters more. The 3 DP option is Infernal Lance, which trades all of this breadth for a per-turn choice on each Knight, including the rewritten Unnatural Fortitude clause that picks between a 5+ invulnerable save and Feel No Pain 6+ when you are attacked.