A unique unit, they start the game as Seed-Embryo "eggs" buried in the ground that hatch later in the game. They have a lower than average PH stat and slightly higher than average WIP than usual line troops, are armed with both shotguns and Combi Rifles all but one option and can access a Light Grenade Launcher as a SWC weapon option.
Unlike most line troops they are not valuable as a generic base unit, but instead fill a niche (in the Shasvastii sectorial especially) as a cheap orders with a defensive gimmick.
Seeds are not an offensive powerhouse and likely wont see much use outside of the SEF sectorial, but they still have some options. All profiles except the light grenade launcher have both combi rifles and light shotguns, the latter offering a +6 within 8" and a template makes them dangerous at close quarters and somewhat negates their poor BS
The light grenade launcher offers a cheap indirect fire option, which is key in the SEF sectorial since there are many FO options that really shine.
Another mention is the FO, which uses their WIP of 13 and better range bands than the combi, This combined with a combi rifle and shot gun means that from 0-24" seeds have many good options.
Seed-Embryo is an imperfect rule, but it still offers some defense for these troops. They will start the game in Camo and at Silhouette of 0 meaning that they are easily hidden and any attacker who wants to get to the back field at the very least has to discover them or use a long skill intuitive attack before clearing them.
Once they are hatched, the combination of a shotgun and flash pulse on the FO makes that profile more likely to win an ARO than their meager stats would suggest
This profile has the Spawn Embryo rule. Spawn Embryo mean that when the unit is unconscious, it still counts as a scoring unit for scenarios like Quadrant Control or Supremacy. Armies with large numbers of Shasvastii might consider taking out enemy units with Shock, Viral, or Monofilament as a higher priority to exploit this rule.
Somewhat corner case, but Seeds begin at a Silhouette of 0, but once hatching are immediately placed standing. This means that they can surprise an unwary opponent by being in ARO position without having to spend an order to stand up.
It is also possible to take other seed-embryo models (Corax Hasht, Spec ops, or Caliban profiles) and take advantage of the fact that your opponent likely thinks they are just seed soldiers. This could be a way to make it appear there are more points "off board" than their really are.
A seed soldier in Seed-Embryo state is very vulnerable. While it might seem nice to jump AD in and kill them while they can't respond, remember that the Shasvasti player likely has an ARO (visible or hidden) guarding them. It would seem like Speculative Fire would be a good option here but be sure to consider your chances. Firing at a 4 to hit is low odds AND grants the seed ARO which they can use to hatch, expanding their options on subsequent orders.
That said, they are still one of the more vulnerable parts of a list and killing them depletes your opponent of valuable orders. They should be considered a soft target from outside of 16" and at any distance while in embryo state.
This profile has the Spawn Embryo rule so when unconscious, it still counts as a scoring unit for scenarios like Quadrant Control or Supremacy. You can bypass this by killing them out right with Shock, Viral, or Mono-filament, or by killing the unconscious models. Shasvastii players may focus extra attention on your sources of shock. Try to use that to your advantage.
Seeds are the third cheapest option for SEF and its not a bad idea to throw them in if you need orders for a list. In CA vanilla there are many cheaper order options, but they could still be considered on missions where you expect to be under assault early such as Decapitation, or if you have a top heavy list that needs to preserve it's order pool (when using an Anathematic or Avatar for example)
Usually though a Unidron or Morat can do the same job with better stats (and for a point cheaper)
Seed soldiers are deployed in the Seed-Embryo state. This means that:
1: They are a Camo Marker 2: They are a S0 Marker 3: They cannot be placed prone
This makes it plainly obvious to your opponent which camo markers are Seeds and which are not, so it is not useful as a "shell-game" tactic to hide your other troops.
A Seed hatches when:
1: at the start of your second turn. 2: when it uses the ARO/Short Skill "Hatch".
SPECIAL NOTE: remember that when they Hatch seed soldiers are placed STANDING. This may mean that they are in LoF when they had previously been safe.
They will benefit from slightly higher armor until they hatch but it is not worth relying on. Try to deploy them where they are covered by other ARO (such as in the LoF of a Q-drone or a Mine's area) or Hidden Deployment will let you counter punch a ramboing enemy. Roof tops or building interiors are also a good option, anywhere that it will take more orders to get to them than it is worth. And if your opponent spends 3-4 orders to kill a 15 point Seed FO you are probably still better off overall.
Active Turn Role
Seeds are there to provide orders.
They can move up on a position making use of their light shotgun to hit multiple foes or compensate for low stats, but largely there is some one else that should be doing that job. There are a few cases where they might be worth using:
A: as part of coordinated order B: when you need to get an objective but don't want to tip your hand and use a better specialist to claim it. C: For a cheap LGL to provide indirect fire.
While in Seed Embryo state the seeds are limited to "Hatch" as an ARO. doing so means they are probably taking a shot in the face, so consider carefully if it is worth using this ARO an revealing yourself. Even at 8" most discover rolls are only a 50% chance of success and failure means the same troop cannot try again that turn.
Once hatched Seeds are like any other budget line trooper. Their light shot gun is nice at close quarters or for clustered foes, and in supressing fire they can be a pain by weight of numbers.
The FO gets special notice because flash pulse is a good ARO tool on WIP 13 models.