The Fast attack slot is kind of a mixed bag- while many are bad, most can be situationally useful. More after the jump.
Flesh Hounds: solution looking for a problem.
Flesh hounds are cheap beasts, durable as bloodletters. They’re the only Khorne without power weapons, so they don’t butcher things. They DO come with Blessing of the Blood God standard. What to do with these... they can pin down units? Sort of? I really can’t think of a purpose for these, leave them at home. They ARE pretty effective anti-grey knights, if you want to get a small squad.
Options... Rending is nice, but Karanak is better. He gives the whole unit Move Through Cover, has a better WS and S, rending, and another attack. Get him if you’re getting Flesh Hounds.
Seekers of Slaanesh: Too fragile for their points.
They’re daemonettes with +1 attack and +6” charge range. They still die really easy, but they can assault through cover well... They have the same options as Daemonettes, so look at that review for my opinions on them.
They’re perfectly ‘meh.’ I find them useless, some people find them deadly. See how they work for you. They're too expensive for being too fragile for my taste- I don't like my 17 pt models dying like guardsmen on the turn they drop.
Screamers of Tzeentch: Usable.
They’re a bit expensive, and they needed some kind of “Intercept” rule, so they never needed worse than a 4+ to hit vehicles. However, if your opponent is moving their vehicles, often, they aren’t shooting either, right? And a silent vehicle is as useful as a dead vehicle!
They are entirely monotask: the only thing they can do is assault vehicles. Use them as suicide melta, or use them more carefully, eating vehicles that have been isolated from the rest of the force. Try bloodcrushers to clear a path and keep assaulting units off their back.
I bring a squad of 5. The main problem with the daemon army is that if someone rolls a landraider onto the table, you basically just have to ignore it: screamers help fill that gap.
Furies of Chaos: Bad.
Furies have the close combat ability of assault Marines, but WS3 and no special weapon access. They have a crappy save. I’d leave them at home: they’re far too expensive and don’t do much. Maybe if they were troops...
Now, there is a niche for them if you're running a fast assault force, with bloodthirsters and winged Daemon Princes, as they can keep up without relying on run rolls. Just a note.
Bonus FW: Blight Drone! Good!
Blight Drones are durable-ish: 12/11/10 means you’ll have to watch your side armor very closely. The BS2 is a detriment, but it is helped by the Autocannons being twin-linked, Vomit being a template weapon, and Phelgm being a Large Blast. Speaking of, that should be the primary purpose of the Blight Drone: move 12”, then fire Phelgm to kill a squad from 36” away. The Reaper autocannons just can’t do enough damage to vehicles to make it really worth it.
The blight drone really benefits from being Daemonic- ignoring shaken and stunned is great when the low AV means they'll be getting more results through.It’s expensive, so you can’t throw it away: keep it back, and have other targets to get shot at.
That’s it for Fast Attack. Heavy Support, coming up!