In short, the Kakophoni are the early iteration of noise marines with psycho-sonic weaponry. But instead of the 40k Salvo style sonic blasters, they have the Cacophony -- effectively a heavy 1 weapon instead.
But the bonus in 30k is that these guys have a special rule called bio-psychic shock. In short, if you cause wounds on your target, the target must take an Ld test modified by the number of wounds caused. Failure indicates more wounds that have AP2 and instant death. Hence the optimal tactica with Kakophoni is to have a large squad of them to ensure the maximum possible hits, the maximum possible Ld modifier, and hence the maximum amount of damage. A large squad of these marines can readily take down squads of enemies with some good die rolls.
The only real upgrades available are for the Orchestrator (squad sergeant). Given their sonic shriekers, I think a power weapon is probably the optimal choice, but can also see that a power fist hidden in a larger squad might be beneficial.
I'd suggest a build along the lines of this:
10 Kakophoni, Orchestrator with power weapon and artificer armour (265 points)
A back field unit with sufficient range to take out enemy infantry squads. Place in cover, or take a rhino and drive closer to your target before unleashing that bio-psychic shock!
Alternatively, a slightly smaller squad drop-podded in to the enemy would also be a nice way to deploy them. So perhaps:
6 Kakophoni, Orchestrator with power fist, artificer armour, melta bombs (195 points)
A squad to drop pod in with Orbital Assault rite of war and take down some light tanks and their contents.
But the bonus in 30k is that these guys have a special rule called bio-psychic shock. In short, if you cause wounds on your target, the target must take an Ld test modified by the number of wounds caused. Failure indicates more wounds that have AP2 and instant death. Hence the optimal tactica with Kakophoni is to have a large squad of them to ensure the maximum possible hits, the maximum possible Ld modifier, and hence the maximum amount of damage. A large squad of these marines can readily take down squads of enemies with some good die rolls.
The only real upgrades available are for the Orchestrator (squad sergeant). Given their sonic shriekers, I think a power weapon is probably the optimal choice, but can also see that a power fist hidden in a larger squad might be beneficial.
I'd suggest a build along the lines of this:
10 Kakophoni, Orchestrator with power weapon and artificer armour (265 points)
A back field unit with sufficient range to take out enemy infantry squads. Place in cover, or take a rhino and drive closer to your target before unleashing that bio-psychic shock!
Alternatively, a slightly smaller squad drop-podded in to the enemy would also be a nice way to deploy them. So perhaps:
6 Kakophoni, Orchestrator with power fist, artificer armour, melta bombs (195 points)
A squad to drop pod in with Orbital Assault rite of war and take down some light tanks and their contents.