skaven are a predominantly combat army that uses different units to counter the threats to the army and as such can win most games if used properly.
Skaven is the kind of army that can be alot of fun and still be competitive with different themes (different clans etc) if your willing to put in the amount of time painting (and deploying). This is a basic overview on the troops and the different clan units (note: this is based on the front of the book list and doesn't include back of the book armies that will be covered in a different article).
skaven rely on numbers and ranks. So don't expect your troops to kill alot of your enemy troops which should make it easier to know what to choose in an army. Every skaven army (except eshin and pestilens clan armies) have clanrats as there mainstay unit. as such they need to be the main of your force, they need to outnumber so taking a unit of 25 is your best bet as it allows shooting casualites and still be able to outnumber. Make sure that your units are taking at least a banner bearer and musician to add to combat res. note: skaven have bad leadership but gain leadership from ranks and therefore need to have there flanks protected i put ratling guns due to there 360 line of sight and the amount of shots but other units work just as well. next are slaves, these are the worst fighters in your army and should be treated as a shooting shield or a thing to tarpit units (need a large unit to do this) so you should take some to survive shooting or to tie up powerful units for magic or shooting into the combat. Remember slaves are expendable and don't cause panic so cn be thrown away with no real consequences. Rat swarms are expendable like slaves but are more expensive so are'nt that useful in my opinion. finally, stormvermin, not very good as they are'nt very elite but are good at holding units up with high armour saves but are generally never taken.
moulder have two monster units that can help role up a battle line or protect your flanks. firstly, giant rats are clanrats but cheaper, faster but less lightly armoured and no banner/musican but can be used as a flanking unit to help add ranks to a fight and can tip the balance in a protracted fight (note: giant rats are clanrats and so are not better fighters so it is better to treat them as flankers and not use them as a separate unit) next are rat ogres, these are good to use in conjunction with the giant rats as they can conbine cheap ranks with close combat attacks but alas the rat ogres are 50pts and so are quite expensive for what they do so are not taken very often (note: packmasters are very important at controlling your beasts but can always attack like spears so don't forget them).
eshin are very useful in taking out units that would mess up your plans such as flyers (remove ranks and therefore leadership) skirmishers etc. firstly nightrunners, these are great as they have an abundance of different weaponry at there disposal and are still quite cheap try taking them with throwing weapons as they can march and shoot making it easier to hit things while you move they can also take slings which give them masses amount of shots but cannot march and shoot these are great for warmachine hunting or wizard hunting for a core choice (note: if you take them with too many weapons they get expensive when they are easy to kill just one special weapon usally works) next are gutter runners who can do exactly the same thing that nightrunners do but better! with poisoned throwing weapons or higher bs but are more expensive and still no save (note: tunnelling teams are only good in small teams so you don't lose that many points to mishap or dying).
skryre is the most destructive and unsafe with powerful weapons at there disposal and can stop as skaven armies bane ,elite units and flanking knights, in there tracks. weapon teams, ratling guns are very powerful as they don't need to hit and can get alot of strength 4 armour piercing shots but are short range at 15" and cannot move and shoot so are easy to target warpfire throwers are more unreliable and shorter range at about 10" put are great at causing panic. many people find that putting it behind there slaves they stop them from getting shot and can be used on harder units once they get into combat (as skaven can shoot into combat) (note: weapon teams can be targeted without penalty as they count as cavalry and are quite expensive so remember to screen them against enemy magic/shooting. next are jezzails, jezzails are great in large numbers as they can destroy those flanking knights with high strength guns while being protected from enemy shooting but are only bs 3 so need large amounts. next are globadiers, also are good knight destroying but are better at killing units in combat or elite infantry, due to ignoring armour they are good in small units as they can sneak around the flanks. finally the warp lighting cannon, very unpredictable with its range and strength best used runnig up the flank and shooting across the battle line they can be very good at taking of ranks in lots of different units (note: with all skaven shooting you can shoot into combat which is a good idea as you will statistically hit the enemy 66% and your guys on 33%).
pestilens is good in combat and add some force but are slightly uncontrollable. plague monks are good because they give a lot of attacks at a cheap price but they have no armour and are slightly more expensive than clanrats but are frenzied so need either a slave unit or rat swarms to control them and stop your opponent from leading them of. next are censer bearers, most destructive combat unit and should just be let loose on the enemies most heavily armoured units due to the toxic gas that only effects them on 6s due to them needing a plague monk unit i recommend putting them in the centre and then a unit in front of them as they will be targeted but shooting and magic (note: slave are good at screening as they are cheap and can stop the frenzy until you want it).
there are only two lord choices a grey seer and the warlord both do different things. the grey seer only the magic user in the army which can accsess the very powerful spells such as plague but is very expensive even without the bell and should only be taken in 2250pts games or higher (views may vary tornament wise), (note:the screaming bell is fun for armies with no shooting or players who like the randomness but are very expensive so are better fro high level games) the warlord is a cheap way to get leadership 10 (provided you have three ranks) and can be used to support your units in combat (note: the warlord is not as powerful as the enemies close combat monsters and should not be used to challenge them etc).
chieftains are hero level warlords and can be used to support your clanrats but is best used as a bsb to confer re-rolls and to add extra combat res to your army (note: put him in the back of the unit so he can't be struck and so he can still confer his bonuses) next are warlock engineers, these are great at what they do which is cast one spell albeit a powerful spell as well as providing some dipel dice and are worth having in an army to replace a grey seer in terms of magic for a cheaper cost. next are plague priests, these are monsters with great stats for a rat and should be in the forefront of the fight with liber bubonius he can add extra dispel dice and cast a spell everynow and again and is very good with a flail, finally an assassin, these are good to defend your heroes or surprise your enemy by striking first and taking out his front line or hero (note: in large games he can be used to take challenges for you general or grey seer to stop them from dying).
- skitterleap: skitterleap is great for when you are not on the bell so you can keep your grey seer out of trouble or to get him to cast magic behind the enemies lines
- warplighting: very destructive good to have and has two levels of power so can take of a couple of ranks or remove outnumber.
- vermintide:great with skitterleap but is'nt a replacement for warplighting
- pestliens breath: the worst spell in the book and cannot be helpful unless very lucky
- deathfrenzy:fun to cast on own units but better to cast on enemy units as you can take them out of the battle ine and destroy them.
- plague:very destructive especially on a shieldwall or gunline can spell doom for most dwarf armies.
try taking a bsb with fear banner and then a grey seer on foot, put a big unit of slaves in combat with an enemy unit (not the best) then skitterleap the banner into the back rank and beat the enemy with 3 ranks bsb and and outnumber and make them autobreak to outnumber by fearcauser.
skaven are a horde army and therefore aren't elite but can be effective if you utilise all the resources presented to them in the book.
for the horned rat!