Genestealers had been known for many years before the Tyranid hive fleets appeared, and it was some time before it was realized that they were part of the same genetically mutable race. Genestealers appear to be a form of scout. Operating on the edge of the Tyranid feeding grounds, they absorb the DNA of sentient species and create small hybrid communities. These hybrid communities radiate a psychic message that draws the hive fleets towards the worlds they have infiltrated. When the Tyranids arrive the whole world is stripped bare. Even its Genestealer scouts and their Hybrids are absorbed back into the hive fleets.
The Patriarch is the Primogenitor (the Great Father) of the Cult, the oldest and most powerful of its kind, with a hold over its brood-web of worshippers as strong as steel. Both physically and psychically is the most powerful of its kind, and its human thralls allow it to understand and work against human society.
The Patriarch is the most powerful character you can have in your Genestealer army, and a character that I would always take in any army of more than 1000 points. I would give him all four powers, as he is still only 172 points, and he is a level 4 psyker. You can give him less powers if you wish, and he will still be a level 4, but if you do you should still always give him Catalyst, so that he can cast it and give its benefits to any brood within 18" (Stealer brood = 8 Attacks, 5+ save on 2d6). Also, the Patriarch causes fear.
Genestealer Magus
The Genestealer Magus is almost human looking except for his bald head, his sickly colouring, and his heavy bone structure. He is the Cult's High Priest, and serves the Patriarch by acting as the Cult's figurehead in human society.
The Magus is a 4th level psyker, with one Tyranid power randomly drawn and three randomly drawn Adeptus powers for 107 points, plus he can be given up to 3 Wargear cards and you should give him a field, or some other type of protection with one of these. The Magus is not a combat character physically, so you must protect him so that he can use his psychics to strengthen your attack.
Always remember that if both the Patriarch and the Magus are lost you must pass a Leadership test with all broods. Those who pass become subject to frenzy but those who fail will break and start to abandon the battlefield.
Cult Icon Bearer
The Cult will often carry some pseudo-religious artifact or unholy icon before them as they march to war. The prescence of such an icon reinforces the fanatical zeal of the brood. The Cult icon is borne by a Hybrid Neophyte who will guard it with the last breath of his body.
You may give the icon bearer one Wargear card, which should be protection. The Cult broods that have a model with 12" of the icon bearer may reroll the dice if they fail a Break test just as with any other army standard, so he is fairly important to your battle plans. You may arm the icon bearer with any combination of equipment from the Armour, Assault, Grenades, Basic, and Special Weapons sections of the Wargear list. I would equip him with better armour and some decent weapons for his own protection and the protection of the icon.
Genestealer Hybrids (Characters)
These are some of the cheapest champions around, Neophytes for 10 points plus equipments, Acolytes for 9 points plus psychic level and equipment. You may include one of either in any Brood Brothers squad. My preference is the Acolyte with level 1 or level 2 psychic mastery. With level 1 you have a psychic champion that costs less than 50 points and adds to the Leadership of your Brood Brothers. I would always include a Hybrid champion in all Brood Brother squads.
These are some of the most deadly hand-to-hand troops in the 41st millennium. They have a M6, WS 7, S6, T4, 7 Initiative, 4 Attacks, and a Ld 10. The Leadership doesn't really come into effect unless you general gets killed, as the Genestealer broods are immune to psychology. They have chitinous armour (5+ save on 1d6). these guys cause fear and they can rip through Terminators like a big Can Opener ("Look out! The Bugs are coming! And they're bringing Can Openers!" -quote by an unknown Terminator Captain).
Hybrid Brood
These can be used three different ways. You can either combine Neophytes and Acolytes to build a versatile tactical brood, arm the Neophytes with assault weapons and the Acolytes with bolt guns and heavy weapons. Or you can build an all Neophyte close combat squad armed with assault weapons, or you can build an Acolyte devastator brood armed with all heavy weapons. These are very useful troops, and along with Brood Brothers should be the backbone of your army. You must have these to support your 'Stealer broods, because 'Stealer broods are only close assault and expensive compared to most armies you will be fighting. If you could only fight other close assault troops, 'Stealers would be enough, but on the battlefield you will be up against troops with firepower that you must counteract, and the only way to do that is with Hybrid broods and to a lesser extent Brood Brothers and heavy weapons teams.
Brood Brothers
Brood Brothers are basically IG and PDF that have defected to the Genestealer Cult. They can also contain criminals, and the diseffected poor population, so their armament can be widely varied, everything from a club to bolt guns. In my experience, such things as bows and crossbows are a waste of time, but swords, autopistols, stub guns, laspistols, and shotguns can be useful.
You can equip your Brood Brothers as a basic mob with a sword and bolt pistol, and they make cheap assault troops.
Or you can equip them with a shotgun for killing lightly armoured low-toughness troops.
Or with bolt guns for taking out such things as Orks, Space Marines, and other higher Toughness troops.
One of my favourite ways to arm them is with shotguns, swords, and bolt pistol for 9 Brothers and one Brother with a heavy stubber, and give them flak armour and grenades.
Remember the Brothers are subject to hatred which aids their close combat ability.
Allies
The Cult may only have allies chosen from the Codex: Chaos army lists.
Brood Brother Heavy Weapons Team
If you have at least one unit of Brood Brothers you may include heavy weapons teams. These teams are exactly like IG heavy weapons teams. They consist of two Brood Brothers with one heavy weapon.
Support Weapons
The Cult army may include support weapon if it includes at least one squad of Brood Brothers. These may be any of the following:
Rapier Laser Destroyer, which is good for killing tanks and heavily armoured foes.
Tarantula, a very versatile anti-grav platform weapon system which can mount either twin-linked lascannons, multimelta (counts as one, not two), twin-linked missile launchers, twin-linked autocannons, or twin-linked heavy bolters.
Now we come to my favourite support weapons.
Mole Mortar, these weapons can totally disrupt your enemy's plans as they can strike almost anywhere on the battlefield with devastating effect. They are somewhat unpredictable, but when they work they work verrrrrrrrrrry well. Just make sure your spotter has a good view of the battlefield.
Thudd Gun, the Thudd Gun can devastate large numbers of lightly armoured close-packed mobs of troops like you will run into with large IG and Ork armies. They're well worth their points. They can also indirect fire, but you must declare your target one turn and then fire on the next, as aligning the weapon takes a full turn.
Vehicles
The Cult is allowed to have the following:
The Wargear List
The Cult Wargear list has a large variety of equipment and you should use this to your advantage. You can arm your troops with a large variety of different combinations of equipment and weaponry. The Genestealer Cult can field troops to meet almost any contingency.
Versus Space Marines and/or Chaos Marines: Use your 'Stealers as assault troops supported by Hybrid tactical and devastator broods. Also, use your tanks and support weapons to destroy Space Marine devastators and vehicles or troops that want to stay back and shoot at you. Right now, the 'Stealer Cult has the best variety of support weapons available, except for maybe the Orks.
Versus Orks: I would use more Hybrids, as they can handle the Orks and it will keep you from being totally outnumbered as you be with 'Stealers, and I would support my Hybrids and 'Stealers with Brood Brothers to give me large numbers of averager troops.
Versus IG: Pretty much the same as Versus Orks, but you need more tank-killng heavy weapons, support weapons, and tanks.
Versus Eldar: You must counteract the Eldar's speed. The way to do this is with a combination of firepower from your Hybrids and Genestealer assault broods with their M6. Pin down the Eldar with devastator broods and tactical broods and destroy them one or two units at a time with your Genestealers.
Versus Squats: You must counteract their heavy weapons and tanks. To do this, use your devastator broods to attack their heavy weapon squads and your support weapons to take out tanks. You can also take out tanks by close assaulting them with heavy weapons, special weapons, and meltabombs and krak grenades.
A Genestealer army has a very versatile group of troops when they are armed correctly. Always think of the mission you will assign to each troop type when purchasing equipment. Do not overarm them for the job you intend them to do, and do not overlook the Brood Brothers in your planning, as they are very versatile and can be used in numerous roles. It is very easy to fall into the trap of using only 'Stealers and Hybrids, but if you do, you will weaken your army. Use the versatility of the army to create advantages for you. It usually comes as a shock to opponents when they run into Brood Brothers equipped with sword, bolt pistol, flak armour, and krak grenades, and them only costing 13 points. These can handle most infantry that you will run into in an Ork or IG army, and they can hold their own against others as they will usually outnumber them. The Brood Brothers can be and should be the backbone of most Cult armies (and I don't mean because of background, I mean because they are very useful). A good Genestealer Cult Patriarch will learn to use these fanatically loyal brothers to their fullest potential. This Genestealers Cult makes a very good combined arms army. Always make sure that you have a balanced force that can support each troop type with other troop types, this is the way to win battles with a 'Stealer Cult army, and always remember the importance of the Cult's leaders.
Good Tactics for the 'Stealer Cult are:
Hammer and Anvil - Set up a group of devastator and tactical broods with support weapons and Brood Brothers in a defensive position to act as your anvil and then attack with 'Stealers, vehicles, and Hybrids on a flank of your enemy (this is your hammer) and drive them inward upon the anvil. It is best if the hammer can attack your enemy's weak flank.
Weighted Flank - This is where you take and set up your Brood Brothers in a line across the full frontage of the battlefield in refused positions in such a way as to give them good cover and good lines of fire. Then setup your Stealers, Hybrids, and tanks on one flank as a strike taskforce and use it to roll up your enemy's flank and destroy his squads by concentrating on one at a time and only moving on to the next when you have destroyed or broken the prior one.
There are other tactics you can use, but I believe the two above to be the most effective with a Cult army.
Back to the Tactica.