Read this. Might help.
http://1d4chan.org/wiki/Warhammer/Tactics/...ords_.26_HeroesHere is my two cents on your list.
LoC L4, Dark Magister, Spell Destroyer 610
(too expensive and your right... he will get sniped.... run kairos instead hes worth triple the amount of points for what he does. If you don't like that... run a Keeper of Secrets. Combine a lvl 3 keeper with the bsb banner that lowers LD by 2 and you just rape units one after another
HoK Firestorm Blade 125
(NO. Get a HoK with a bsb, armor of khorne, and magic banner0
HoK Soul Hunger, Juggernaut 175
(keep him on foot)
HoT MoS 165
26 Bloodletters FC, Icon of endless war 367
(get rid of the icon and make this unit at least 30 or combine the two units into 40)
18 Bloodletters FC 246
(get rid of this unit to either increase the horrors or make the make the bloodletters bigger)
18 Horrors, Standard 228
(you always want FC on everything. make this unit bigger)
3 Flamers 105
(Flamers are amazing... get 2 units of 6 and watch them rip units to shreds)
3 flamers 105
(same as above)
2 Fiends 110
(make these fiends two separate units for war-machine hunting)
3 Bloodcrushers, FC 260
(blood crushers are awful in 8th edition... way to expensive... they are better for 40k)
If you do decide to take KoS take this in mind.
The Keeper of Secrets is probably one of the best choices here, solid magic ability, excellent close combat skills and a ton of wacky gifts that can really **** with your opponent! On top of being a greater daemon, it's fast (M10, I10, always strikes first) and has armour piercing. The Daemon Lore of Slaanesh can be amusing, especially against low-Ld armies, but it can also make this guy's ability jump from good to cheating. Speaking of which, avoid the urge to drop the 100 pts. for Spirit Swallower; the KOS' isn't a longevity monster (see below), s/he's a morale rapist. That said, one of the funniest configurations is the "come at me, bro," whereby you tool your KOS with Siren Song + Soporific Musk and/or Allure of Slaanesh, march 20" out towards your opponents hardest cavalry unit, cast Phantasmagoria if you rolled it (enemy Ld tests on 3d6 choosing the highest) and use Siren Song. This forces a unit to either flee or charge the Daemon and since most cav units will be able to charge, they will rush at the daemon and strike AFTER the KOS - that's if they pass their leadership test due to Allure of Slaanesh! Then once they break, they roll an extra D6 and choose the lowest. For additional fun, grab the Temptator gift and if your opponent was smart/dumb enough to have a character (or even his general) in that unit, you can have the satisfaction of making said character your ***** and using him to attack the unit he's in - serious fun!