It is always good to post the point level thanks.
Ok lets start with your
Lords:
Your LoC is built fine, however since it looks like your taking special characters so Fateweaver is just a more durable, and stronger LoC for prox the same points. I do reccoment Fateweaver based on how competitive your group is. If they are non comp players or if they whine I dont recommend him.
Heros:
HoT: Built right I generally run Life/Shadow with him. If you can make points for a disc then fly him around if not then hide him behind the Bloodletter unit.
Blue Scribs: Fun special character. If your running special Characters I suggest swaping him out for Skulltaker (overcosted) but hes pretty cool model, my favorite model in the army book. Or you can run Masque(comp like Fateweaver) who syncs well if Great Icon of Despair.
HoS: solid build, remove Allue of Slaanesh for Tormment blade. It confers +1 Attack for 5 points

I am not a fan of seekers, but try them out.
Core:
Furies solid
Bloodletters: It would be awesome if you tell us what they are equiped with. Like is their a Standard Bearer, Musician, Bloodreaper? If not I highly suggest to add all 3 of them models. I also suggest adding Icon of Endless War to help get these guys into CC faster. I also just noticed that you dont have points for a HoK. I HIGHLY recommend this guy for the bloodletter unit. Give him Armor of Khorne and hes set.
Pink Horror unit: Extremely fragile. I only suggest horror units if they are 35+ models in it. Pink horrors are extremely fragile and are only worth their points when gathered in mass for a higher Wiz level.
Rare:
Flamers fine, maybe add +1 model. Some players may suggest adding another unit of 6, i do not.
Fiends are overkill. make them at 2+ per unit at most. They are meant for charge blocking and warmachine hunting. Not meant to "tank" other units. I say drop them down to 2 so you can add more Heros/ Core.
Special: I am not a fan of seekers..