Mass Combat for 5e¶
These rules resolve a battle too large to play out in full. Rate each side, roll for the outcome, and roll for losses.
Using These Rules¶
Use normal 5e combat rules for twenty or fewer creatures, when a single powerful monster is the centerpiece, when the players are personally fighting, or when the action happens at one spot such as a gate or a bridge. Use mass combat rules for a wider battle or for a clash the players are commanding rather than fighting in. A battle may use both.
Command¶
Every army requires at least one commander. A commander may lead creatures whose combined Force Power (see Step 1) is no greater than the number below, taken from his own XP value. For a PC, treat his level as his CR.
| Proficient in | Command Cap |
|---|---|
| Martial weapons and heavy armor | Full XP value |
| One of the two | Half XP value |
| Neither | Quarter XP value |
A 5th-level fighter is treated as CR 5 and may lead an army of up to 1,800 Force Power. A 5th-level wizard may lead up to 450 Force Power.
Edge¶
Edge is anything that favors one side or anything that it has that the other side does not that would help it to win the battle. In the next steps, determine Edges for each side.
Step 1: Edge from Numbers and Force Power¶
Compare the number of creatures on each side. Find the larger side's ratio on the table below and give the appropriate Edge Bonus.
| Larger side leads by | Edge Bonus | Larger side leads by | Edge Bonus |
|---|---|---|---|
| Up to 1.1:1 | 0 | Up to 10:1 | +6 |
| Up to 1.5:1 | +1 | Up to 15:1 | +7 |
| Up to 2:1 | +2 | Up to 20:1 | +8 |
| Up to 3:1 | +3 | Up to 30:1 | +9 |
| Up to 5:1 | +4 | More than 30:1 | +10 |
| Up to 7:1 | +5 |
Force Power. A creature's Power equals its XP value divided by 100. Add up the Power of every soldier on a side to get that side's Force Power. Do not include PCs, named heroes, or the commanding officer in a side's Force Power if they will be fighting using normal 5e combat (see Heroes in a Battle).
| CR | Power | CR | Power |
|---|---|---|---|
| 0 | 0.1 | 4 | 11 |
| 1/8 | 0.25 | 5 | 18 |
| 1/4 | 0.5 | 6 | 23 |
| 1/2 | 1 | 7 | 29 |
| 1 | 2 | 8 | 39 |
| 2 | 4 | 9 | 50 |
| 3 | 7 | 10 | 59 |
Once Force Power has been determined for each side, compare the two totals. Find the larger total's ratio on the table below. That side starts with the indicated amount of Edge Bonus.
| Larger side leads by | Edge Bonus | Larger side leads by | Edge Bonus |
|---|---|---|---|
| Up to 1.25:1 | 0 | Up to 5:1 | +7 |
| Up to 1.5:1 | +1 | Up to 7:1 | +8 |
| Up to 1.75:1 | +2 | Up to 9:1 | +9 |
| Up to 2:1 | +3 | Up to 12:1 | +10 |
| Up to 2.5:1 | +4 | Up to 20:1 | +11 |
| Up to 3:1 | +5 | More than 20:1 | +12 |
| Up to 4:1 | +6 |
For example, if one side has 180 Force Power and the other side has 100, then the ratio is 1.8. That side would get an Edge Bonus of +3.
Step 2: Edge from other sources¶
Each side collects Edge Bonuses from the table below, on top of any bonus from Step 1. A side gains the listed Edge Bonus for each Edge that it has and that the enemy does not. The DM may add other Edges to reflect other special circumstances.
Count an Edge once. When one side's Edge answers the other's, such as cavalry against pikes, the two cancel.
| Category | Edge | Edge Bonus |
|---|---|---|
| Training | Better trained than the enemy* | +1 to +3 |
| Training | Better armored than the enemy* | +2 |
| Resilience | Has healers | up to +2 |
| Resilience | Hard to put down (regeneration, undead that keep rising) | +2 |
| Resilience | Resists or ignores the enemy's main damage type | +2 to +4 |
| Resilience | Cannot be frightened (undead, constructs, fanatics) | +2 |
| Ranged | Outranges the enemy and can shoot before they close | +2 |
| Ranged | Many ranged attackers facing a single monster or a handful of large creatures | +6 |
| Ranged | Area damage against packed troops | +4 to +6 |
| Ranged | Area damage against troops who are spread out | +2 |
| Spells | Spellcasters who control the field (walls, webs, fear, slow) | +2 to +4 |
| Movement | Faster than the enemy, able to flank, or cannot be pinned down | +2 |
| Movement | Can fly or otherwise stay out of the enemy's reach while attacking | +4 to +6 |
| Cavalry | Charging loose infantry in the open | +4 |
| Cavalry | Charging in any other open-field situation | +2 |
| Cavalry | Charging into set spears, pikes, or rough / wooded / uphill ground | −2 |
| Ground | Holds high ground, chokepoint, or good cover | +2 |
| Ground | Prepared defenses, fortifications, or walls | +2, +4, +6 |
| Circumstance | Enemy surprised | +4 |
| Circumstance | Attacking on multiple fronts | +2 |
| Circumstance | Enemy tired, hungry, or bloodied | +2 |
| Circumstance | Fighting for homes or making a last stand | +2 |
| Command | Capable commander still in the fight | +2 |
* Step 1 already covers training and armor; these Edges only count if the Edge Bonus from Force Power is 0.
Fragile casters. Spellcasters who deal area damage or control the field are devastating until the enemy reaches them. If the enemy has cavalry or archers that can attack unprotected casters, those casters give no Edge.
Step 3: Find the Edge Margin¶
Total each side's Edge Bonus from Step 1 and Step 2. Subtract the smaller total from the larger. The difference is the Margin, and it belongs to the side with more. For example, if one side totals 8 and the other 5, the higher side is favored with a margin of 3. If both totals are equal, the margin is 0. The DM flips a coin or decides which side counts as favored. If one side feels like it deserves a slight Edge, give it +1 or +2 instead.
Step 4: Decide the Outcome¶
Roll a d20 and add the Margin. Read the result from the favored side's point of view.
| Total | Result |
|---|---|
| 3 or less | Decisive victory for the underdog |
| 4 to 7 | Bare victory for the underdog |
| 8 to 9 | Stalemate |
| 10 to 13 | Bare victory for the favored side |
| 14 to 18 | Decisive victory for the favored side |
| 19 to 22 | Rout won for the favored side |
| 23 or more | Annihilation won for the favored side |
Step 5: Determine Losses¶
Find the result on the table below. For each side, roll the dice shown and add the base to get its losses as a percentage of its total creatures.
| Result | Winner losses | Loser losses |
|---|---|---|
| Stalemate | 10 + 3d6 % | the same |
| Bare victory | 8 + 2d6 % | 20 + 3d6 % |
| Decisive victory | 6 + 2d6 % | 30 + 3d6 % |
| Rout | 4 + 2d6 % | 40 + 3d6 % |
| Annihilation | 4 + 1d6 % | 65 + 4d6 % |
Loss percentage. The loser's losses are a percentage of the loser's army. The winner's percentage (and both sides' in a stalemate) is based on the smaller army. For example, if 200 knights have 5% losses against 100 goblins, who lose 70%, then 5 knights are lost and 70 goblins are lost.
Remove a side's losses proportionally from each unit type. If units vary widely in strength, instead figure losses as a percentage of Force Power and remove units until that much Force Power is gone.
Wounded. The winner holds the field and can recover half of its losses as wounded. In a stalemate, both sides can recover wounded.
Prisoners. To find how many prisoners the winning side can take, take Edge as a percentage and multiply it by the losses of the losing side. For example, if the winning side had an Edge of 5, and the losing side lost 100 soldiers, then it can take 5 prisoners. Both sides may take prisoners in a stalemate. A hero on the losing side is assumed to be taken prisoner if he did not escape.
Troops who never rout. Undead, constructs, and fanatics do not flee. A force that would be routed or annihilated fights where it stands. The winner's losses climb two rows up on the table (a rout's winner takes bare victory winner losses).
Fighting to the last. A force that will not flee, such as undead, constructs, or fanatics, takes losses as for an Annihilation outcome. If the losing force was in the open, the winner's losses climb two rows up the table. If the losing force was fighting from a well-defended position, determine the winner's losses based on its own force as for a Stalemate outcome, with a limit of up to three times the destroyed force's number.
Chases. If the winner has cavalry or other fast troops and the result is a rout, the loser is run down. Treat it as annihilation, and lower the winner's losses. This does not apply against a force that never routs.
Commanders. The losing commander is taken prisoner or killed unless he can escape.
Special Situations¶
Heroes in battle. Instead of including them in mass combats, it can be satisfying for heroic characters to first fight a normal combat for a key objective that can shift the battle, such as hold the breach, kill the warlord, or burn the siege engines. The winning side may gain +1 to +4 Edge Bonus depending on the circumstances. When heroic characters command an army, they may also make key decisions before the battle, such as choose advantageous ground or setting a trap. Attempt to model these in Step 2 above.
Sieges. A siege may be resolved in stages: attacking intact walls, breaching, a field battle if the garrison sallies or a relief force arrives.
Single monsters. A lone dragon, giant, or other great monster is not a soldier in a line, and mass combat rules are not well-suited to handle these situations. Treat such monsters as heroes.
Stalemates. If a stalemate outcome is reached, another battle can be joined immediately. Repeat steps 1 through 5.
Example¶
Six hundred orcs and four ogres storm a fortified garrison: 100 guards, 100 archers, and 50 veterans dug in on a palisaded hill. Two player knights hold the gate.
Force Power. Orcs total 616, garrison 475 — a ratio of 1.3 to 1. The orcs gain +1 Edge from Force Power.
Numbers. Orcs 604 bodies vs garrison 250 bodies — a ratio of 2.4 to 1. The orcs gain +3 Edge from Numbers.
Edges. The garrison has fortification (+2), high ground (+2), and better range since the orcs have no archers (+2), totaling +6. The orcs' Force Power and Numbers Edges are already tallied above (+4). Subtracting, the garrison is favored with a Margin of 2 (garrison 6 vs orcs 4).
Hero scene. The hero characters hold the gate against an ogre and its retinue in normal combat, and win. Their side gains +2, bringing the garrison's Margin to 4.
Outcome. The garrison rolls a 7 on the d20, plus 4, for 11 — a bare victory for the garrison. The garrison keeps the hill.
Losses. Bare victory: winner loses 8 + 2d6 percent, loser loses 20 + 3d6 percent. The winner's percentage is of the smaller force (the garrison, 250). The loser's percentage is of its own force (604).
- Garrison (winner): rolls 7 on 2d6 for 15%. 15% of 250 = 38 casualties. Half are wounded and recover because the garrison holds the field: 19 dead, 19 can recover.
- Orcs (loser): rolls 12 on 3d6 for 32%. 32% of 604 = 193 casualties. The orcs broke and fled; their wounded are captured or killed with the rest: 193 lost.
Prisoners. The garrison's Margin was 4, so it can take 4% of the orc losses, or 8 prisoners.