My party just finished a mission I had set on the Tyranid-besieged world of Castobel and during the mission one of the characters started to analyze the possible future the world. An interesting question came up, which I could not answer at the moment, but then again I didn't need to since the characters did not have access to that information at that moment: How is Castobel supplied food-wise?

There is really two options:

1) Castobel was net food importing world, receiving supplies from other worlds untill the Tyranids cut the transit lines.

2) Castobel is capable of producing its own food somehow.

Now I think this is very interesting question for the future of the campaign as it affects hugely on which kind of solution to Castobel siege is most expedient for the Imperium. As the world itself is almost lifeless and all biomass is inside the Hives the Tyranids are losing energy and mass by sieging the Castobel unless they can break into the Hives.

If Castobel is dependant on imported food the most expedient solution (even though ultimately very cold-hearted) is to leave the place alone to starve and waste no resources on it, letting Nids starve themselves slowly there.

If, on the other hand, Castobel has huge food production facilities hidden somewhere, then the Tyranids might actually gain a net biomass increase by conquering it, further strenghtening the Hive fleet Dagon... In this case Imperium has two choices: Defend the world or use Exterminatus right away.

What do you think?

They're only starving outside until they break in, at which point the gains may be enough to outweigh any loses. I could afford to sleep in a hotel opposite outside a bank for a long while as I planned my robbery of the vault, and I'd still only loose out overall if I never got into the vault.

In any case, starving the hive will shorten the siege, and if you want to 'waste' biomass, the Imperium needs to extend it as much as possible.

The situation might have varied from hive to hive. Some utterly reliant on imports with others being self-sufficient, net exporters or some mix of the above. So one hive could currently be full of starving defenders about to be overrun while another could supply the first hive - if it weren't for the tides of tyranids in between.

Siranui said:

One of the reasons why 'nids are doing not-so-well on Castobel is that they trusted on this and went empty stomached when the second hive to fall obliterated itself in nuclear pyre, denying their flesh.

Siranui said:

Only if you actually CAN resupply the siege. As I see it with Tyranids already on the orbit, atsropathic communications cut due to Shadow in the Warp and planetary orbital defences already shred sending a resupply fleet to the system is like dropping supplies straight to Tyranids maw.

I guess that it's time for some cannibalism, then!

I just started a mission in Castobel for my players. One of the things I've often wondered was how did the Ruinous Powers react to the Tyranids? The Shadow of the Warp likely harms them (or at least hampers their influence), the swarm is incorruptible (so far), and they eat their most likely candidates for corruption (humans among others). My thinking is that the chaos powers would try to slow down or stop the Tyranids, if only to protect thier own next meals.

So my group is heading to Castobel and investigating the cult/gand activity and they know that while 2 hives were destroyed, 1 was destroyed presumably by overloading its reactors and immolating itself. I threw in what the Inquisitors found out, which is a chaos ship was briefly detected in orbit above the city and detected the teleport signature that the chaos types use, 48 hours later the city was destroyed in nuclear fire. The presumption being Chaos is fighting back now, and this was not only an attempt to prevent the swarm's next meal but also one of Chaos's characteristic mass sacrifices.

So the Kill Team will likely have chaos and tyranids to contend with.

qcipher said:

I agree entirely. It seems to me that the forces of Chaos would oppose the Tyranids and Necrons as bitter as the Imperium does, since those two races are inimical to continued life at all in the Galaxy. The Chaos legions may not hate the named xenos like they do the Imperium, but most of them should be able to see the danger.

I think Necrons also have a special place in the corrupt heart of any Daemon or Traitor Legionnaire since they are reputedly the only race that can actively prevent Warp from functioning in certain areas of space... Would be funny if Chaos guys and girls observed a Deathwatch Kill Team enetring a Necron ruin. On the one hand they would love to see the Necrons destroyed, on the other hand they would be afraid that Deathwatch gets their filthy loyalists hands on to some anti-psychic technology. What to do?

Easy. The chaos boys and girls sneak in after the killteam, wait for a shootout or for the killteam to come back out. They may end up ambushing a killteam. Best case scenario, they come upon a killteam and necron force who've smashed up each other.

Regarding Chaos and Tyranids,

Realm of Chaos Vol 1 i think mentions a damaged discarded Black Legion helmet was found inside a hive by a boarding party.

Advanced Space Crusade gives rules for using chaos forces in boarding actions on tyranid ships and mentions imperial forces encountering chaos marine forces still fighting inside tyranid vessels.

Picture the faces of the kill team fighting in a hive ship seeing power armoured figures alos fighting and in the confusion of battle each presumes the other an ally and fights side by side as comrades till the ichor clears and each discerns the markings and loyalty of the other!

Or thye guardsmen seeing the thunderhawk above them that rains down assualt troops into the terrible tyranid foe saving their lives only to then see their wounded being turned into a living altar of screaming dying men as the chaos marines start building the basecamp in their own campaign against hive fleet dagon!

Castobel seems like an enjoyable and suitably grand scale backdrop for a few Deathwatch missions, and I am hoping to get my players there sometime soon, but I am unsure what the best and most compelling missions would be to keep things unique and not another "kill synapse creatures" event. Of course, I suppose I could predate the mission relative to the fluff, say, before a certain hive fell, and their mission could be to infiltrate and overload the reactors of the hive right as it fell, then somehow get out in time...

Other than that though I would not mind doing some siegebreaker type hit and run missions. Destroy the pyrospore batteries, or what have you. Perhaps sabotage spawning pools to waste yet further biomass, or maybe specifically slay major synapse creatures, but only do so when the swarm is physically under the fire of a hives big guns, stunning lesser tyranids and leaving them disorganized right when their under fire. Of course, this means locating hive tyrants and the like and stalking them without being discovered until they are under fire, and then killing them while risking being hit by the same artillery that the killteam hopes to strand the swarm members in range of. Hmm, maybe that has some potential.

Or possibly attempting to capture lictors and then use their pheremone thingies to draw crucial forces away from the hives during assaults, or into ambushes. presumably the outskirts of the hives have lesser buildings and such which are rubble and would provide suitable terrain for such actions.

Hrm, commandeering a spacehulk/great rok full or orcs and flinging them into the midst of the tyranids might be suitably interesting. Always nice to have the xenos killing each other. Also involves orks, which I have yet to have a good exposure for this campaign, unlike tyranids, who are featured rather a lot.

You could also have your players investigating the disappearance of another Kill-Team, when they arrive they find evidence of what happened it shows evidence of a new Tyranid creature which has not been categorized, pict recordings of a massive creature, statements from surviving troops in the area that sort of stuff. They identify the creature and start to track it's movements and locate any weaknesses it may have eventually finding an confronting it, use the Dagon overlord from Mark of the Xenos with a little modification if necessary.