slammeister wrote:
2 x Black legion retinue
2 x Cult marines (Thousand sons / Death Guard 1 in each)
6 x Obliterators (3 in each)
1 x Havocs (in the Tzeench formation)
2 x champion / icon bearer / daemonic pact (1 in each)
2 x dreadnought (in with tzeench)
This is 1800 points, so with the Banelord, you have 3 formations that are each pushing 1000. That's cutting seriously into your flexibility. Also, with big barrages, more units is just more targets.
You've got some mixed role formations here. It's okay to have some multi-purpose formations, but specialists are more efficient and the sheer size of these formations is more than offsetting the gains you get from the flexibility. If you focus more, you'll end up with a greater variety of specialists for more punch and increase the tactical options enough to actually improve your flexibility, even without the generalist formations.
For example, if the Tzeentch retinue is going to be primarily a shooting/area denial force, then the assault options are somewhat wasted. You might keep a pact around, just in case you end up in a position to assault, but that's not going to happen often, so the rest of the summoning kit is not likely to be helpful. TSons are largely assault as well, though their 4+RA "meat shield" capacity might be okay on a shooting formation.
The reverse is true for the Nurgle formation. You can bring down the shooting elements so it can focus more intently on closing and assaulting. A token Obliterator is probably enough, if you even need that.
Retinue (Tzeentch) + Havocs + 3 Obliterators + Pact = 675
This can garrison with 25 shots on Overwatch, daring the opponent to come at you, even with armored vehicles.
Retinue (nurgle) + Cult + Pact/Champ/Icon = 550 (Maybe 625 with Obliterator.)
This can garrison forward to help reach assault range. You can summon 3+ save daemons that don't cause BMs as meat shields, averaging 8 at a time. That is a huge help in letting it cross the board and pressure the opponent. Also, since the formation only moves 15cm and the plan is to close with the enemy, this makes a good formation to possibly summon a Great Unclean One. It's not a shooting formation, but it has enough firepower that shooting while closing is worthwhile, and you might even (rarely) end up in a situation where something like Sustain Fire makes sense.
Both can take a fair beating and retain effectiveness as well.
Quote:
2 x black legion bikes (champion, icon bearer and daemonic pact in each)
You're almost never going to need Icons in a Bike formation. Bikes are too fast for most daemons to keep up with, so you are rarely going to want to keep the daemons from turn to turn. If you want to keep a Tzeentch-aligned bike formation kitted out for summoning a Lord of Change, that's probably OK but outside that, you really only need a Pact to give a bit of oomph once you get close. Adding ~4 daemons is still an appreciable bump.
Also, if you're trimming down the summoning kit, Raptors are a better buy, so you can replace the stripped down Bikes with Raptors.
Overall, 2 formations that can summon a GD is all you need. The above changes would leave you with one Retinue and one Bike formation able to do so. You could probably also trim the LDs slightly. If you figure ~10 for the Nurgle Retinue's meat shields and a couple assaults where the unkilled LDs are going to go back into the pool, you can probably get by with ~15 lesser daemons.
Between the Retinues and the Bikes, you can easily trim 600 points. If you are concerned about AA after dropping the Obliterators, you can pick up an air formation and still have enough for another serious formation. For example, aircraft and termies, both of which increase your "deepstrike" capabilities.
===
For a more direct answer - First action, Banelord sustains fire on the arty company. With 12BP, you should be able to cover it all and average 3 kills (2 if the entire company is actually in cover when deployed). Killing just a couple arty units will make a huge dent in their firepower (2 kills + 3 BMs = only 4 unsuppressed units, 3 kills is only 2 unsuppressed). If you have aircraft to hit them, you might even get lucky and break them on your first activation before they fire.
Plus you can possibly cover a Russ or two with the Banelord barrage just for BMs to slow them down.