ISC - What to buy

[Peoples Champ]

Looking at getting an ISC force and wanted some guidance.
I was going to get the box plus a few extras.
Idealy I want a force I can mix and match up to about 150 points total.
What are the must gets for ISC?

[Berf]

The box is a very good choice. It provides a well-balanced team, able to cope with anything your opponent can come up with
If you want to play with more points than the recommended 100 points, you can go with one 40-10 combo (Hadakauma or Kami + one of the little drones), depending on your strategy (beat'em all style with the Hadakauma or Try to kill me style with the Kami). Or take the 25-25 path for support, choosing between the Ashigaru (Defense), the Konchu (Weakening) and/or the Ubume (specific killer (low PSI)). But be warned that not all the Missions are balanced when you play with more than 100 points.
For a standard 100 points ISC team, mixed with the starter, I advise trying the Komuso (control) and/or the Rikishi (defense, but quite multipurpose really, if you know how to play it). These two are my favorites, and a team with them and the Ronin (for brawl) can be really effective. You can also go with a 25 + 10 combination as a replacement of a 35 fighter. For exemple the Ubume and the Gaki can be very scary, as the Gaki lowers the enemy PSI and the Ubume attacks can be performed with a PSI difficulty rather than a VIG difficulty. The Gaki can also restrain enemy actions and this can be a good combination with the Ashigaru, making your team a very defensive one, good for keeping objectives.
My personal choice : Komuso, Rikishi, Gaki, Ashigaru. These four a very good, but require some skills as they are not the most effective in close-combat.

[Taban]

Thanks Berf for this very detailed answer.

I will just add that the Drone colors show their use on the battlefield : this can be a way to select your models (either all of the same color or a mix of them depending on the gameplay you are looking after or the missions you might want to play))

Yellow = support
Green = exploration
Black = infiltration
Carmin = combat
Blue = protection
Grey = control / leaders

[Peoples Champ]

Thank you both very informative.
One model that caught my attention is the Green Mamushi. What are the benefits or negatives of that figure?

[Berf]

Aaah, the Green Mamushi, I forgot about it.
A very good fighter, especially since we made some changes with its stats recently. The new stat card can be downloaded normally, although I just saw a major typo in this new card (Shame on us ! The Constriction special ability requires one SP and not one PA, which is already a typo since it's AP in english. Oh well, i'll just flail Taban )
The Mamushi then...
First, the major inconvenience : it cannot attack. Never.
But that doesn't mean it cannot hurt your enemies ! It has this Constriction ability, to strangle the s**t out of anyone, even other Drones, if you win a VIG roll in opposition with your target. It inflicts 3 wounds in the torso and reduces the Protection by one for this 'attack'. What are the advantages of this ? Well, first of all, 3 wounds in this location is an almost sure way to get the enemy 'wounded' (use the red characteristic), so it is effective to soften up the enemy before the other Drones come to deliver the fatal blow. And since the torso is a 'central' location for everybody, it means you won't have to alter your hits too much in case you made a bad location roll. You can use this ability only once per turn (of course) but it can scare most enemies out of the way if some major badass is near too (Hadakauma, Ronin, Samurai, why even the Rikishi can be dangerous for someone wouded in the torso).
Now, the advantages : the Mamushi cannot be hurt in the arms or the torso, since it doesn't have any location for these. So if you're opponent roll a location of 3 or 4, he must relocate his roll or the attack has no effect. Combine this with the VIG 5 and the armor, and the Mamushi can be very hard to kill.
It has a high movement capacity. 5 in SPD means it can interrupt your opponent well, it ignores the scenery elements while moving (very useful), is immune to Slowdown (and Fear) and can bury itself and then come out anywhere on the battlefield. It has virtually one of the highest potential in movement in the entire game.
I think I covered the major aspects of the Mamushi. Very useful, but not alone. It needs the other Drones more than they need it. It is a very good support for your fighting troops or a good hunter of the opponent's support (Shamans, shooters,...). Oh, and it can eat a lot of SP if you are not careful