he Tyranid hive fleets have now been assailing the Imperium for 250 years. In this time, whole Chapters of the Adeptus Astartes have been lost in the maelstrom of battle along with countless millions of Guardsmen. But now deeper knowledge of the Tyranid way of war is being gathered, every fragment paid for with human flesh and blood.

One realisation has been that the swarms that descend from the hive fleets in the early stages of an attack are often significantly different from those that follow. The list in Codex Tyranids is designed to represent a typical swarm. This article, however, features a variant Tyranid list that deals with the first wave - the seeding swarms - the harbingers of doom to countless worlds and their cultures. Note that you will still need Codex Tyranids to use the seeding swarm.

Mycetic spores are more than just the Tyranid versions of drop pods, they are a vital part of their ecology. The Tyranids are a space-dwelling race but their prey is terrestrial. Mycetic spores are one of a number of different spore types used to seed target planets. Some types affect the weather, others the flora and fauna, and some even introduce new species. Militarily, without mycetic spores the hive fleet's ships and their Norn Queens would have to risk planetary defences and waste valuable energy to feed. With mycetic spores the hive fleet can gather around the prey planet and bombard it with seeding swarms, only descending themselves when all resistance is crushed and all the juicy bio-matter is ripe for consumption. The release of seeding spores is analogous to a person pouring, sniffing and sampling a fine table wine before drinking it. The main course may be yet to come, but the meal has started.

Mycetic spores are not as sophisticated as drop pods, but the sheer numbers of spores dropped ensure that some will get through the planetary defences. As with any contested landing, the first few minutes are critical. If the seeding swarms can establish safe landing sites then Tyranid reinforcements can be directed to those locations and, in short order, massive concentrations of Tyranids can be built up ready for the hive mind's signal to attack. If, however, the seeding swarms can be defeated then there is nowhere safe for successive Tyranid swarms to land and planetary defences will continue to claim a high toll. With no chance to build up, the Tyranids that have landed can be counter-attacked and driven from the planet altogether.

No two hive fleets are exactly alike and no two swarms from the same hive fleet need be exactly the same. Subject to this, seeding swarms have some similarities because of the job they do. If you think of a swarm as a single large predator then, if it is a complex swarm relying on several genus operating almost symbiotically, can be hamstrung by planetary defences upsetting its balance. Even against a planet with minimal planetar defences, heavy losses can be incurred, so the creatures in the first swarms down have to be robustly simple in their approach.

If robustly simple sounds right up your street, read on, because the seeding swarm is a different type of Tyranid army. It relies on the most numerous creatures in the swarm - those that occupy the Troop slots on the Force Organisation chart. Heavy losses during planetfall are cancelled out by launching successive waves, with each subsequent brood having the same role as its predecessor. If one is destroyed the next will replace it. Other broods manifest a chemical imbalance that ensures that they are unusually hyperactive. They are faster, stronger and even more ferocious than their kindred, but the rate at which they expend their energy causes them to burn out within minutes of their landing. These ploys are represented in game terms by some changes to the way the mission to be played is selected, variations in army composition and, most importantly, two special rules which characterise seeding swarms.

The seeding swarm has a Strategy rating of 4. This means that when determining the scenario category the Tyranid seeding swarm player will roll four dice and select the highest rather than simply rolling a single dice. If the seeding swarm player gets to choose the scenario then the Tyranids will automatically be the attackers and the scenario category will be Battle. Page 129 of the Warhammer 40,000 rulebook explains the rules for choosing a scenario and mission more fully.

All three Battle scenarios use the Deep Strike special rule. This is detailed on page 132 of the Warhammer 40,000 rulebook. All models in Tyranid seeding swarms MUST arrive on the table by this method with two exceptions: broods with the Infiltrate ability may deploy conventionally in accordance with the mission rules. Lictors may use Secret Deployment as described in Codex Tyranids.

For other scenario categories if there is a Deep Strike option in the scenario then it may only be used by Tyranids such as Gargoyles, that can Deep Strike as part of their normal profile. Other broods are set up as specified for the mission. These missions can be considered to represent the seeding swarm being attacked when it is already on the ground.

Seeding swarms use the following units from Codex Tyranids:

0-1 Hive Tyrant, Tyrant Guard may accompany the Hive Tyrant but cannot be an HQ choice themselves.

Tyranid Warriors.

Tyranid Warriors, Lictors (no more than one Lictor per brood).

Hormagaunts, Termagants, Genestealers.

Gargoyles, 0-1 Haveners.

0-1 Zoanthropes (no more than one Zoanthrope per brood), 0-2 Carnifex.

The only Tyranid models excluded from a seeding swarm are Biovores and Ripper Swarms. Biovores are not included as the hive fleet will already have saturated the target planet with a spore mine preparatory bombardment if the mission calls for it. Ripper Swarms will come later when organised resistance is crushed and the business of consuming the planet's bio-matter is begun.

If you use a personalised Hive Fleet you may still use it as a seeding swarm. If you have a new genus of Hive Tyrant or Carnifex then you may use 0-1 Hive Tyrant and 0-2 Carnifexes as shown on the Seeding Swarm Composition chart. Ripper Swarms never feature in seeding swarm forces so cannot be used. New genus's of Tyranid Warrior or Gaunt can be used freely in whatever category of the force organisation chart Codex Tyranids specifies (see Hive Fleet List Force Organisation on pg38).

Some broods may be mutated to maintain terminally-high adrenaline levels. This state is induced quite deliberately by the hive mind to turn a brood into even more vicious killers than normal.

Any normal Troops choice can be selected to be Ferocious. To do this they replace a Fast Attack choice on the Force Organisation chart. The Troops choice is now a Fast Attack choice, leaving the vacated Troops choice free and reducing the number of Fast Attack choices remaining by one. A unit may not be both Ferocious and Without Number (see later).

The effect of Ferocity is boosted Strength and speed (+1 Strength, +1 Initiative). Ferocious troops move in a blur, their bodies wracked with uncontrollable shaking and their eyes lit by berserk rage.

Ferocious troops must assault if there are any targets in range and must perform a sweeping advance instead of consolidating whenever the option exists.

When a brood is subject to Ferocity the normal proviso that Deep Striking troops are destroyed if they land within 1" of an enemy model does not apply. When deploying a Ferocious unit using the Deep Strike rules, any enemy models that are also under (or partially under) the large template may be attacked in close combat. This is done in the Assault phase and is conducted normally with the Tyranids counting as charging. Such is the Ferocious troops' state of agitation that they burst from the spore almost as soon as it lands and leap on the nearest enemies without hesitation.

This is shown in the diagram. The large circle shows the Ordnance template used to deploy the Deep Striking Tyranids.

Tyranids cannot live long in such an agitated state and Ferocious broods suffer appalling attrition due to biological system failure. At the end of each Assault phase of the Tyranid player's turn, whether the unit has been in close combat or not, resolve a Strength 2 hit on each boosted brood member, with no Armour save. These tests do not begin until the brood is actually on the table.

Whilst the negative effects of augmented Ferocity is potentially crippling, these broods are able to swiftly overwhelm key positions while other Tyranids are still emerging from their mycetic spores, their sacrifice opening up the defences for those that follow. If the Tyranids are not arriving by mycetic spore then they deploy normally, but otherwise follow the Ferocity rules.

Any normal Troops choice can be selected to be Without Number. To do this they replace a Heavy Support choice on the Force Organisation chart. The Troops choice is now a Heavy Support, leaving the vacated Troops slot free and reducing the number of Heavy Support choices remaining by one. A unit may not be both Ferocious and Without Number.

Without Number has the effect of making the brood the first of a series of waves, each consisting of an identical brood. Without Number broods are always subject to the Sustained Attack special rule (see page 137 of the rules). When the brood is destroyed or if it is falling back and the Tyranid player chooses to remove it, then an identical brood re-enters play during the next Tyranid turn, arriving by mycetic spore. The replacement brood can therefore Deep Strike even if this is not allowed in the scenario being played. If the scenario allows Sustained Attack anyway then Without Number broods re-enter play using the Deep Strike rules rather than coming on the table edge.

If one of the incarnations of the Without Number brood is lost while performing a Deep Strike then its replacement arrives in the following turn.

A seeding swarm arrives from reserve in a piecemeal fashion, so early on in the game you will have to play according to what arrives. Taking a Lictor and some Genestealers to deploy conventionally can be quite effective as it gives the enemy something to focus on and ensures that at least part of your force is immediately available.

Because you will be landing amongst the enemy, firepower is not as important as normal, a seeding swarm can get away with being armed solely with tooth and claw but it will need some monstrous creatures or loads of rending claws to deal with enemy tanks.

The hive mind's Leadership is essential to sustain the swarm through the heavy losses it will doubtless take. Don't skimp on Synapse creatures because the consequence of running out is a lot of Morale checks against very low Leadership. Early in the game you may only have a single Synapse brood or creature on at any moment in time. If so, concentrate on keeping them out of the line of fire but within Synapse range of the lesser creatures.

Broods taken as Heavy Support with the Without Number rule are very useful and can be hurled into combat secure in the knowledge that they will be back. Large Hormagaunt broods are ideal choices in this regard. Their combat abilities are formidable, being nore than a match for Imperial Guard and Eldar Guardians. With an advantage in numbers they can even eat the Space Marines - remember Space Marines have got to fail their armour saving throws some time!

Ferocious broods are marked for death the moment they are selected, so it does not pay to invest too many points in them. They are great for tying up dangerous enemy units who are in the strongest defensive positions. If they arrive later then they become really useful reinforcements as their spores drop right into ongoing combats or onto enemy fire bases. Small broods of Genestealers can be particularly useful in this role as in their boosted state they are able to lay waste to pretty much anything they can jump on before they die out themselves.

So how do we balance it all up? The best way of showing the true potential of the seeding swarm menace is via an army list. I designed the following list to be representative of a seeding swarm and a swift glance should show how scary this variant of the Tyranids can be. I have used the standard Tyranid list with no biomorphed genuses although there is no reason not to use your own hive fleet. The seeding swarm is in fact absolutely ideal for a hive fleet that specialises in hordes of the smaller critters.

I have selected one HQ - a very tough Hive Tyrant whose presence should cause a lot of worry. As he is quite likely to appear in the middle of the enemy forces the Psychic Scream should be effective. When playing against Andy Chamber's swarm recently I was impressed by the way Warp Field protected his Tyrant from my missile launchers, so I have casually stolen the idea. There are times when a venom cannon, for all its three shots at Strength 8, just isn't the tool for the job, so I have selected Warp Blast to frighten Space Marines and punish anyone grouping together too tightly.

I really like the new Tyranid Warriors so I have included three broods as Elite choices. I have found the safest place for a Tyranid Warrior is often in melee rather than being a target, so I have equipped them all with rending claws to ensure that they can hurt well-armoured enemies. Venom cannons are the only Tyranid guns with decent range so I included one in each brood. Devourers are great close-up and I reasoned that there would be times emerging from a mycetic spore when a hail of death might be useful.

Due to the seeding swarm rules, I knew that I would be using lots of troops and decided to stick to Genestealers and Hormagaunts. The plan is to land in numbers and get into melee very quickly. Three Hormagaunt broods make up my Troops selections and I included a mutant Hive Node in each of them. The vagaries of Reserves and Deep Strike being what they are, it is quite possible that these broods will have to operate away from the hive mind for some time, so having a Leadership value of 10 will help prevent them from adopting instinctive behaviour when I least want it.

Two Hormagaunt broods were selected as Heavy Support to benefit from the Without Number rule. These will ensure that the swarm will keep coming and that even on the last move of the game there may be more Tyranids arriving. The other Heavy Support pick HAD to be a Carnifex as these rampaging monstrosities have the capacity to rip, rend and tear their way through virtually anything. Even the normally invulnerable Land Raider is just so much food packaging to the Carnifex, so it is certain to draw masses of fire.

For Fast Attack choices I took a standard Gargoyle brood, primarily so that I had a few more things to shoot with on landing, and also because with their bio-plasma the Gargoyles can be surprisingly dangerous. For the other two choices I took Genestealer broods with the Ferocious rule. There will inevitably be games where the decision point is whether one or two firebases can be held. The Genestealers will be hurled at the firebases. I don't expect them to live but I do expect them to get their claws bloody very quickly. Ideally the damage done by these broods will be sufficient to give the hordes of Hormagaunts and Tyranid Warriors the chance to get the job done.

As is often true with armies lacking firepower, by giving your opponent lots of difficult target choices you maximise the chance of them getting it wrong at the key time. In this army the Tyrant. Tyranid Warriors and Carnifex are what will really worry an opponent. Everything else is really a decoy but a potentially deadly decoy if not treated with the proper respect.

I make no claims that the seeding swarm is invincible, indeed I can tell you for certain that it isn't. What I do claim is that it's the type of army that will have your opponent watching the game from behind the sofa and developing a tendency to look up a lot, just in case. All in all, seeding swarms have terrifying potential, but throwing your broods at a planet is a gamble that could cost you. The resultant battle is likely to be intense and brutal.

What more could you want? Have fun.