Mass Combat for D&D 5th Edition

So, I like D&D 5th Edition. Quite a bit, actually. However, it's not perfect, and it does have one glaring hole that I love to put in my games these days: Mass combat.

I love Mass Combat. I love the idea of big army fights, but abstracted down to manageable levels, rather than putting the RPG session on hold to play a miniatures wargame. I love this concept so much that I managed to work mass combat scenes into my last two campaigns (Necessary Evil and Deadlands Reloaded). Mass Combat rules were one of those things I really hoped would be in the 5e DMG, but was not present, unfortunately...so when I was staring at a scenario that could easily break out into mass combat (Episode 6 of Hoard of the Dragon Queen), and the DMG wasn't a huge amount of help in this case, I put my thinking cap on...and went back to what had worked so well in the past:

I dug out Savage Worlds.

No, I didn't suddenly convert the game over to Savage Worlds. I love Savage Worlds, and I'll get back to it soon enough, but there's more than a few things that it does that has, and can, help me in D&D5e.

Like Mass Combat.

Unfortunately, Wounds and Bennies and Knowledge (Battle) don't immediately get along with D&D. I was looking at a potentially uphill battle...until I remembered that Shane Hensley had applied those same rules to a system that didn't have a leadership-style tactical skill, and the system also had a hit point system.

And so I dug out Army of Darkness from Eden Studios, written by Shane Hensley and featuring an adapted Savage Worlds Mass Combat system...and I went to work with the two books in hand, as well as the D&D books, and kitbashed in the following system (which got a playthrough Saturday night, and went pretty well):

D&D 5e Mass Combat Rules

Adapted from Savage Worlds and Army of Darkness rules by Shane Hensley

This is an abstracted Mass Combat system for D&D5e, adapted from the rules that appear in Savage Worlds and the Army of Darkness RPG.

Like the rules from which this is derived, you don’t need to worry too much about every little detail, as these are meant to be a cinematic and free flowing abstraction of mass combat.

Setup

List the various troop type and reinforcements.

Each Round

Everyone makes an attack roll using the appropriate ability (Melee or Ranged), against the average armor class of all the non-individual units. A roll of 1 is a Critical Failure. Rolling under the Armor Class is a standard failure. Meeting or beating the Armor Class is a Success. Beating the target Armor Class by five or more is an Extraordinary Success and a natural 20 is a Critical Hit.

Melee

Critical Failure: In the chaos of war, you never see the foe flanking you, and a brutal attack threatens to lay you low! You sustain a critical hit from the troop type that you were battling. Resolve as normal. Add nothing to your side’s Battle Roll.

Failure: You wade into battle but your allies are beaten back. You find yourself surrounded and you suffer grievous wounds. Sustain three hits from your opponents (one automatic). You add nothing to your side’s Battle Test.

Success: The fields run red with blood and you cut a swath through your foes, but their blades and their clubs extract a price from you. You add +2 to your side’s Battle Test, but suffer two counterattacks (one automatic).

Extraordinary Success: You lunge deep into the field of battle and set the pace for your allies, beating back the enemy forces and instilling fear in them. You add +3 to your side’s Battle Test, but suffer a counterattack.

Critical Hit: You become an avatar of carnage, swatting aside your foes and crushing them beneath your feet. Add +4 to your Battle Test and no counterattacks can be made against you.

Ranged

Critical Failure: You expose yourself at the wrong time and get hit by a dead eye marksman. You sustain a critical hit from an enemy. Resolve as normal and add nothing to your side’s Battle Roll.

Failure: You emerge from cover but the enemy is waiting and the damage you inflict does not remotely match the damage you take. You sustain two counterattacks (one automatic) add nothing to your Battle Roll.

Success: You pick apart the opposing forces with several well timed shots. You do sustain return fire, but your opponents know you were there. Add +1 to your side’s Battle Test, but you are on the receiving end of a counterattack.

Extreme Success: You time your shots expertly and inflict several casualties, many of whom never saw the attack coming. Add +2 to your side’s Battle Test and sustain no counterattacks.

Critical Hit: You rain death from the skies, picking the most opportune places to fire your attacks to maximize the damage. Add +3 to your side’s Battle Test and ignore any return fire.

Battle Test

The Leaders of each side roll Intelligence and add the modifiers from the Battle Test Modifiers Table. The higher total wins.

+2           The Leader’s army is roughly twice as strong or numerous as the foe.

+4           The Leader’s army is roughly three times as powerful as the foe or better.

+2           Leader’s army is protected b major fortifications.

+1 to 4  Any additional tricks and advantages. Rule of thumb: Damage dealing powers equal to half the damage die type, spells bonus is equal to the level of spell. For instance, a Dragonborn's breath weapon is a +3 (half of a d6), while a Mirage Arcane is a whopping +7 as you completely disorient the opposing forces with magic. Use common sense with spells, though. If it doesn't make sense to grant a bonus, don't grant a bonus. Named NPC warriors (on either side) can contribute bonuses in this fashion as well.

Morale

Roll Morale for each unit type, as per the DMG, but only for the side that lost the battle roll. However, if the leader of that unit has a Charisma score higher than the unit's Wisdom score, then they make the Morale roll at Advantage. Once that unit loses half of their forces, however, they make the roll with Disadvantage. If they fail the Morale roll, their natural inclination is to break and retreat or surrender. The leader can push them to continue fighting, but losses in the next phase will be doubled. If you wish to add further modifiers to this roll, you can apply them as they make sense. Some suggestions follow:

+2  if the unit is unable to properly retreat.

+2 if the unit is made up of fearless creatures (like golems or undead).

+2 if the unit is defending a fortification.

Losses

The leader for each side makes  Constitution Saving Throw for each unit type in their army, against DC 10 if their side won the Battle Roll and against DC 15 if their side lost the Battle Roll. If the winning side beat the losing side by 10 or more in the Battle Roll, then the winning side makes this roll with Advantage while the losing side makes it with Disadvantage. Each unit type that fails this roll loses 10% of their starting forces for each failed roll. If they are being forced to fight after failing a Morale roll, then they lose 20% of their starting forces. If they roll a natural 1, then those losses are doubled once more, for a truly crushing combat round.

PCs and Hit Dice

There are several options that allow for automatic hits to PCs, which can add up over time. Given the nebulous timekeeping nature of mass combat scenes, feel free to let the PCs use their Hit Dice in between rounds.

"Zoom Ins"

If you have a big badass Death Knight leading his Legion of the Damned on one side, and the PCs are gathering the Freemen of the Halcyon Coast on the other side, don't let the Death Knight get cut down as a random casualty. Heck no, describe how that Death Knight is ripping through soldiers left and right with his wicked sword, maybe describe his Hellfire Orb blasting apart the archers one round...but at an appropriate moment, "zoom in" on the Death Knight coming face to face with the PCs, so the Paladin of Vengeance and the Moon Druid and the the Wood Elf Ranger with his Wolf Companion can attempt to end the threat once and for all (though the Death Knight probably has a handful of Skeleton Warriors with him as well), and play that battle out...and sometimes not all the PCs are going to be there, because it doesn't make sense, so they are still fighting off the hordes and doing Mass Combat-y stuff instead...but these Zoom Ins should have a huge effect on the battle (maybe instead of General vs General(s), it's a group trying to take a group of catapults so they stop firing at the oncoming forces, that sort of thing).

Ultimately, there's a lot of discretion in your hands with these rules. The modifiers can stack up pretty high, but given the swinginess of 20 sided dice, that's almost necessary. Our first run through went pretty well...they managed to take every combat round, even after the opposing NPC generals hit the field (the first round was a complete, fog covered sneak attack before dawn), and the zoom in was brutal and bloody (resulting in one PC death and another very near PC death), but it all felt suitably dramatic and everyone loved how the session went.

There's a lot of room for interpreting other abilities in the rolls. I very nearly gave the Ranger with Hordebreaker Advantage on his Melee rolls, because he's specifically designed to fight through multiple enemies. You could give a Raging Barbarian their damage bonus to the Battle Roll and I think it's both thematic and doesn't break anything. That kinda thing. Like I said, lots of discretion.

I'm pretty sure I'll revisit these again before the Tyranny of Dragons is complete.

Thoughts? Alternate ideas for Mass Combat?