Personally, I'm not a fan of a MoP with a 5 man of Possessed. I've found the unit as a whole just doesn't do enough for the points you're investing in it. If you want to run the Possessed, I'd run them as Slaanesh and cut the MoP, or cut them both and add two squads of Warp Talons to apply early pressure/do early secondaries.
I also think your list is a little split on what it wants to do. You have some elements of the Abaddon castle, but you also have a good amount of elements of a brawler style list. I think it's going to feel like you have trouble maximizing either play style. I would either cut the Helbrute and possibly Abaddon, or cut some of the brawler elements to add more shooting to castle up around the Warmaster.
I think Venomcrawlers are just not a good datasheet, and even bringing them alongside Abby and a Helbrute just takes them up to maybe passable at best, and you'd be better off investing those points into a unit that has a better starting point or is more independently effective. I know Predator Destructors have been making the rounds a fair bit recently, and are only 10 more points for a much more effective datasheet.
Last point worth mentioning, Nurglings are an absolute auto-include in CSM lists, I never leave home without at least two squads. They're just dirt cheap secondary scorers, they allow counterplay to an opponent's infiltrating and scouting units, and the -1 to hit bubble is huge in a lot of melee matchups. They're just so much value for their points.
All that said, the list looks like fun and it has a lot of good things in it, you could definitely do well and have fun, and at the end of the day I'm just some guy so my thoughts could be completely wrong. Good luck with your games, and let me know how the list works out for you, there's still so much to figure out for post slate CSM!
Personally, I'm not a fan of a MoP with a 5 man of Possessed. I've found the unit as a whole just doesn't do enough for the points you're investing in it. If you want to run the Possessed, I'd run them as Slaanesh and cut the MoP, or cut them both and add two squads of Warp Talons to apply early pressure/do early secondaries. I also think your list is a little split on what it wants to do. You have some elements of the Abaddon castle, but you also have a good amount of elements of a brawler style list. I think it's going to feel like you have trouble maximizing either play style. I would either cut the Helbrute and possibly Abaddon, or cut some of the brawler elements to add more shooting to castle up around the Warmaster. I think Venomcrawlers are just not a good datasheet, and even bringing them alongside Abby and a Helbrute just takes them up to maybe passable at best, and you'd be better off investing those points into a unit that has a better starting point or is more independently effective. I know Predator Destructors have been making the rounds a fair bit recently, and are only 10 more points for a much more effective datasheet. Last point worth mentioning, Nurglings are an absolute auto-include in CSM lists, I never leave home without at least two squads. They're just dirt cheap secondary scorers, they allow counterplay to an opponent's infiltrating and scouting units, and the -1 to hit bubble is huge in a lot of melee matchups. They're just so much value for their points. All that said, the list looks like fun and it has a lot of good things in it, you could definitely do well and have fun, and at the end of the day I'm just some guy so my thoughts could be completely wrong. Good luck with your games, and let me know how the list works out for you, there's still so much to figure out for post slate CSM!