This optional rules module is intended to facilitate military operations on a grander scale – planetary invasions, uprisings, and protracted warfare. It leans heavily on the original 1990 Mighty Empires, pdf versions of which are quiet readily available after Games Workshop released them for free around the time of the 2007 edition with its far more rudimentary rules.
Scale
As planetary campaigns are map-driven, some thought should go into scale. Recommendations are 60 kilometer hexes (edge to edge) with 1 week turns, 300 kilometer hexes with 1 month turns, or (if planetary battles and sieges are to be fought, but not intended to be in focus) condensing the entire planet into one single “hex” using nominal 1 year turns (though some fights might be resolved in far less time).
You may map out only a relevant part of the planet or the entire world, in which case mapping onto an unfolded icosahedron is recommended.
Terrain and Features
For the movement rules it is important for the map to show terrain that is impassable or dangerous for large bodies of troops to cross. Also the locations of any important special features, such as spaceports, settlements, dig sites, mining complexes, planetary defense silos, and similar should be noted. Some features may be hidden or otherwise unknown to the characters.
Armies
The position of armies are tracked on the planetary map. Armies follow standard Epic army compostion, consisting of a minimum of 1 company card of troops and up to 1 special and 5 support cards per company card. A single army may contain a maximum of 2,500 points of troops. Warbands operating with an army do not count against this maximum. Record the exact composition of each army, as well as noting any permanent losses from individual cards. Multiple armies may operate together. For some special force compositions, it might be considered permissible to spread cards across multiple armies (e.g., a titan heavy army in excess of 2,500 points may have only a single battlegroup as its sole company card and thus be unable to fulfill the normal minimum requirements for a second army), but these armies then always have to operate together.
Forces
The difference between a force and an army is that a force is not formed up for movement and battle on the map. It is instead a pool of available troops, from which one or more armies may be formed.
The troops available can be expressed either as a points budget along with factions and possible restrictions (e.g., a force consisting of 5,000 points of Imperial Guard with no super-heavies, or a force consisting of 2,000 points of Squat infantry plus 1,000 points of Tech Guard), or by directly listing the type and number of army cards (where possible, use company cards instead of multiples of support cards) but without having to assign support and special cards to individual companies (e.g., a force consisting of 10 Imperial Guard tactical companies, 4 Imperial Guard support companies, 1 Imperial Guard Leman Russ company, and 2 Imperial Guard Stormblades).
The location of a force should be indicated on the map, this being their primary mustering ground and depot location.
Surface Movement
Armies follow the movement rules, including scouting, for banners from Mighty Empires with the following exceptions:
Instead of rolling on the scouting table, make a Navigate (Surface) test, a success is required to successfully scout a route.
An army may scout and move 1 hex per turn for every full 10cm of Move of its slowest unit (minimum 1 hex), units mounted in transports may use the transport’s Move for this purpose.
In addition, an army may be force marched 1 additional hex, in which case roll a D6 and consult the chart below.
| D6 | Effect |
| 1 | Lose D6x100 points of troops and D6 points of supplies |
| 2 | Lose D6x100 points of troops and D3 points of supplies/td> |
| 3 | Lose D6x50 points of troop and 1 point of supplies |
| 4 | Lose 1 point of supplies |
| 5-6 | No effect |
When trying to find a route through dangerous terrain, use the Mighty Empires Route Chart, but for any perilious route found use the above Forced March Chart to determine potential losses.
Use the Mighty Empires Scout Skirmish Chart when scouting a hex with one or more enemy armies.
Abstracted Battles
When opposed armies meet in battle, you may either play the battle out using Epic rules, or use the battle rules from Mighty Empires with the following adjustments:
Double all strength values on the Combat Table.
Before choosing battle plans, both armies test Command. If one army succeeds and the other fails, the failing army must choose and reveal its battle plan before the successful army chooses its plan.
In addition to the strategic modifier from battle plans, modify by 1 in favour of an army for every two troop types (from the list of infantry, walker, cavalry, vehicles, flyers, knights, super heavy vehicles, and titans) that it fields and that the opponent does not field.
Instead of character casualties, a roll of doubles for the random modifier indicates the loss of a high value target, this might be the retinue (in which case roll for Casualty Recovery), a unit represented by a special card, a titan, a commissar, or some other stand out part of the affected army.
Double all points losses from the Battle Result Chart.
Double all points losses from the Pursuit Chart. A roll of 3 may mean the retinue is captured if appicable.
Especially in the lead-up to a battle he retinue – and warband – may try to influence things by embarking on raids, sabotage missions, or espionage operations, to eliminate key enemy assets, learn of battle plans in advance, or any number of other goals.
Fortresses & Sieges
Again following the rules from Mighty Empires, defending armies may retreat into suitable defensive features, such as fortresses, citadels, or shield-domed cities.
Apply all relevant adjustments (such as the doubling of indicated points losses) to the battle rules to the siege rules as well. Do not apply the additional modifier for troop types not present in the opposing army.
Orbital Bombardment
Most relevant likely when playing out sieges using Epic, but potentially also relevant – if more dangerous – in other battles, an army with friendly ships in orbit over the battlefield, may be supported with orbital bombardment strikes. In the advance fire segment of the combat phase, a ship may place a barrage template anywhere on the battlefield. Roll to scatter, using the scatter and artillery dice. Orbital fire is notoriously inaccurate, so, even if a Hit symbol is rolled, still move the template a number of cm indicated by the artillery die in the direction of the small arrow integrated in the Hit symbol. After completing the scatter, repeat the process a second time. If a Misfire result is rolled at any time, there is some issue (e.g., the strike goes wieldy off target landing outside the battle area, the weapon systems fail. An orbital bombardment strike has 9 BP and a Target’s Save Modifier of -6.
Army Logistics and Reorganisation
At the end of a turn, armies can be reorganised, that means that within an army, cards can be shifted, split, or combined provided there are enough individual units, e.g., in an army containing a Leman Russ company card, this could be split into three Leman Russ support cards.
Reorganisations can also be carried out between armies in the same hex, or between a force and any armies in the same or an adjacent hex as the force.
Also at the end of a turn, any armies and forces on the map check their logistics. Supplies are measured and tracked in turns worth (i.e., weeks worth, months worth, or years worth) of supplies. Supplies can be carried in the logistics train of an army or can be stockpiled somewhere, such as within a fortress complex.
Reduce the available supplies of each army and each force by 1 point. If no supplies are available, i.e., there were 0 supply points when the deduction was called for, roll a D6 and consult the chart below.
| D6 | Effect |
| 1 | Lose D6x100 points of troops and army may not move next turn |
| 2 | Lose D6x50 points of troops and army may not move next turn/td> |
| 3 | Lose D6x50 points of troops or army may not move next turn |
| 4 | Army may not move next turn |
| 5-6 | No effect |