Using The Army Lists
To make a choice, look in the relevant section in the army list and decide what unit you wish to have in your army, how many models there will be in the unit and which upgrades you want (if any). Remember that you cannot field models that are equipped with bio-weapons and biomorphs that are not shown on the model. Once this is done, subtract the points value of the unit from your total points and then go back and make another choice. Continue doing this until you have spent all your points.
Using A Force Organisation Chart
The army lists are used in conjunction with the Force Organisation chart from a scenario. Each Force Organisation chart is split into five categories that correspond to the sections in the army list, and each category has one or more boxes. Each box indicates that you may make one choice from that section of the army list, while a dark toned box means that you must make a choice from that section.
Diagram: Standard Missions Force Organisation chart. Compulsory: 1 HQ, 2 Troops. Optional: 1 HQ, 4 Troops, 3 Elites, 3 Fast Attack, 3 Heavy Support. Layout shows HQ and Elites at top linking down to two Troops boxes, a Fast Attack box, and a Heavy Support box.
The Standard Missions Force Organisation chart is a good example of how to choose an army. To begin with you will need at least one HQ unit and two Troop units (dark shaded boxes indicate units which must be taken for the mission). This leaves the following for you to choose from to make up your army's total points value: up to 1 extra HQ unit, 0-3 extra Elite units, 0-4 extra Troop units, 0-3 extra Fast Attack units and 0-3 extra Heavy Support units.
Army List Entries
Each army list entry consists of the following:
Unit Name: The type of unit (referred to as a brood in a Tyranid swarm), which may also show a limitation on the maximum number of choices you can make of that unit type (0-1, for example).
Profile: These are the characteristics of that unit type, including its points cost.
Number/Brood: This shows the number of models in the unit, or the number of models you may take for one choice from the Force Organisation chart. Often this is a variable amount, in which case it shows the minimum and maximum unit size.
Bio-Weapons: These are the unit's standard bio-weapons.
Options: This lists the different bio-weapon and biomorph options for the brood, and any additional points costs for taking these options.
Special Rules: This is where you'll find any special rules that apply to the brood.