the new codex but as always some things perform better than other or just need to be used in a
This is the current core of my warband. 4 squads of Chaos Space Marines. I have 2 units set up for melee.1 units has 2 flamers and a Champion with a Power Sword, the other had 2 Melta Guns and the Champion has a Power Axe. The shooty units both have 2 Plasma Guns and a Champion with a Power Sword. They all have a Icon in the unit but unless I have spare points it's just there for aesthetics. The only one i regularly pay for is the Khorne units (Flamers) as it allows them to reroll their charge and they are usually mounted in a Rhino (reviews on those another time). I have 2 Missile Launchers and 2 Multi Meltas ready to go on my other 2 squads as they can have dual Heavy Weapons now and with "objective secure" being back now, it would be worth having 2 units more static but packing a longer range punch. This would also give me 6 units to fill a full Battalion detachment.
In terms of how Marines play in 8th, it's tricky. In cover for a bonus save they can be hard to shift. In the open with no support they may as well be Guardsmen with big guns. Power Armour is still good but with even heavy bolters being AP-1 they can kill Marines pretty easy now. But the points drop has made them more desirable. Overall with upgrades you can save over 40 points on a squad of these guys. It's a shame the Marks are just for Strategem cards and Icons and have no real in game effect but it does keeps the armies simpler to build and play.
I have had varying success with Marines so far. One game 10 of them holding a Grey Knight Grand Master in combat for 4 turns for minimal losses and other games where they are shot off the board before bringing their bolters to bear. But that's part of the game I suppose. I still love the look of these guys swarming the enemy and being able to soak up as much as they dish out. A lot of the other armies do not have access to such versatile troops as Marines.
Tactics wise these guys are used as I need them. I will always take a Rhino but it varies which unit I put in there. Most common it is my Flamer unit as they can take most things bar Large tanks or Monsters. Occasionally it will be a Plasma squad if I have a further out objective that I would rather they camp unit back up arrives. The flexibility of transports in this sense now is a huge bonus.
I would always take these over Cultists (I have 20 but they are not all painted yet). They make a Chaos Legion look like a Legion still and they can be a rock upon which your enemy breaks.
I always wanted my Black Legion to look like a Warband and by keeping my units looking similar but with colour and build variations they are a more fun to build and paint. Some of my guys sport shoulder pads from other chapters including Grey Knights and Deathwatch. Some have Space Wolves weapons and tokens/icons from various other sources (even an Ogre Kingdoms Banner). I will definitely keep this a running theme across the army (wait until you see my Terminators).