One combination which creates a highly versatile assault force goes as follows:
-Chaplain Grimaldus with 2 Cenobyte Servitors
-Command Squad with Banner of the Emperor Ascendant and Drop Pod
-Skyhammer Annihilation Force with:
*2 x Devastator squads, each with 10 Marines and 4 Grav Cannons, Drop Pod
*2 x Assault squads, each with 5 Marines, Jump Packs, an Eviscerators, and a Vet Sgt with PF/LC
-2 x Scout Bikers with Locator Beacon, 5 Bikers
-2 x Assault Centurion squads with melta guns
-2 x Fast Attack Drop Pods
Attach Grimaldus and Cenobytes to Command Squad and their Drop Pod (I am working off the assumption that Cenobytes count as “Wargear” and so Grimaldus can still attach to other units with them in tow, kind of like Iron Priests with Cyber wolves can attach to other units; this is controversial and some don’t agree with this interpretation, but for now, I am going to go with it).
Use the Scout Bikers to bring in the Devastators, Assault Marines, and Grimaldus Command Squad precisely where you want them. Make sure the Assault Marines are within 6″ of Grimaldus, his Servitors, and the Banner. With their ability to charge turn 1, they combine quite handily with the +1A, Zealot, and FNP handed out by the Grimaldus, Servitors, and the Banner. This means that the Assault Marine squads each get 4 x S4 AP- attacks, 5 x S4 AP3, Shred attacks, and 3 x S8 AP2 Unwieldy, Armourbane attacks on the charge. Throw in Zealot for Fearless and re-rolls to Hit and Feel No Pain for better survivability and these units should be able to roll up even very tough opponents in close combat.
Devastators combat squad to provide four different units that each put out 10 x Grav shots a turn to deal with hard targets and the Scout Bikers provide fire support, objective grabbing, and even the ability to charge and add some more weight in combat when required on later turns.
Finally, the Assault Centurions provide vehicle popping power with their melta guns and Sieg Drills, plus they benefit quite a bit from Grimaldus, Cenobytes, and the Banner to make them more durable, potent, and reliable.