Marshall is a bit expensive at low points.
In general you'll want transportation for your troops. Lasbacks if you want to go shooting or rhinos if you must run straight at the enemy.
Take some of the following
Typhoons are cheap.
Assault termies with furious charge in a landraider.
5 Termies with 2
CML/
ACs with tank hunter.
Preds/vindis with/without
PotMS.
Shooty drea with tankhunter.
Seriously though typhoons are cheap.
I would recommend having your troops do the same function. So if you want them to sit back and shoot it is better to have mulitple units doing that. If going forward, go forward in numbers. This is really important for
BT as leadership things mean the enemy can blast 5 men off an objective at range and fearless in
cc means they can squash units before getting to new objectives.
Each squad can have one special weapon and further one model can have a good
cc weapon or heavy weapon. The good
cc weapon can only get 1 or 2 hits so this isn't as good as you would have thought. I would suggest having two 5 man squads one with the lascannon and one with the missile launcher, then giving each squad a plasma gun. In general I would go for lascannons as they are cheap in points and are cheap in $ as other armies mainly want
ML.
Good luck burning witches