One area that I found lacking in the otherwise magnificent Lex Arcana roleplaying game was mass combat. The characters, admittedly, play the equivalent of “secret agents” in an alternative Roman empire, but the military plays a central part in the politics and activities of the Empire. In our campaign, the characters have uncovered a plot by a group of Vandals and Othrogoths to cross the border in force as they are being pushed west by the other tribes behind them. Word has been sent to Rome to gain reinforcements for the imminent attack, but it’s now a waiting game. The next episode would have this force assault across the Danube on the castra at Submuntorium — the gateway to Augusta Vindelicorum and the both the main roads of Aurelia and Claudia Augusta.

It’s going to be a big fight, with 1700 Romans in the castra against a force of around 8,000 migrants with half of that fighting age men. The 4-1 odds are mitigated a bit by the need for the barbarians to cross the Danube, then get by the wall of the German Lines. There are siege engines in play — battering rams, catapults, and ballista — so a lot of moving pieces. I could have just pre-decided the results, but wanted the players, now in positions to aid the commander of the defensive force, to have some kind of impact. I needed rules of a light legion-scale fight.

My first pass was to make some lightweight rules that used the units as NPCs, but that seemed a clunky. I settled on using Lex Arcana‘s prolonged action rules to handle it.


During a force on force event, both sides must roll for successes, with a total number of successes based on certain goals. Difficult for the tests is determined by a combination of the number of forces or the obstacle (castle walls or gates, etc.) that need to be overcome.

For the test, the leader of the particular unit — be it a contubernium or a legion, rolls the DE BELLO of the type of NPC found in the uint or it’s commander. For instance, a century of Roman soldiers would be represented by a Legionaire or a Centurion, as per the NPC examples in the rulebook. Characters can use their TACTICS or other skills that might be appropriate to aid in the roll because, well, they’re the heroes in the story. As always, a GM is encouraged to alter these to suit the tastes. For overcoming a castle wall or gate, a smaller unit might have a higher DT.

Ex. The 2nd Century of the II Audriatrix engages a turma of barbarian cavalry. Rome needs a DT3 on the unit’s DE BELLO and three successes to win the day. The barbarians need a DT9 and nine successes, but the GM decides the mobility and use of bows gives them an advantage and lowers the DT to 6. Both sides roll their DE BELLO with a specialty of Tactics for the centurion commanding the 2nd; the barbarian commander a 2d5 for his men. Both sides roll: the centurion is havimng an off-day, it seems, with a 5 result. He’s got a single success. The barbarian rolled a 9 — a success!

Both sides continue the engagement. This time, one of the player characters chooses to rally the troops with a command test on DE SOCIETATE of 12 — and between the centurion’s 7 and the PC’s they score a 14 — a complete success that will rout the remaining barbarian forces. The barbarian commander is on a lucky streak and got a 10, allowing him to reroll and add to the original score. He rolls a 3, giving him two successes. The Romans needed three successes and have four — the barbarian force is destroyed, utterly. The barbarians got a total of three successes, six short of what they needed. The day belongs to Rome.

How many people did the respective units lose? In the case of the barbarians, it was a complete disaster. They’re either all dead, or a few escaped according to what the plot needs. The Romans, hower, got hit hard on that last foray. So how many are injured or wounded? The GM could fudge this — a third of the unit (3 successes of nine needed) so 33 imjured or dead.

Another way would be to use the size of the unit attacking as a base. The turma — 30 barbarians — scored one and then four successes. Taking a tenth of their size (3) as the base, then multiplying it by their success (the first only just succeeded, so 3 injured; and the second foray gave them double the damage, 6 for a total of 9 dead. (In this case, I’d go with 9 dead and about 25 injured.)

It’s not perfect, but it squares with the existing rules of Lex Arcana.