Mass Combat

GM Reference

War can happen in any campaign that involves politics, kingdoms, or large-scale conflict. How you handle it at the table is entirely up to you — the mechanics below are one structured option, not the only one and arguably not even the most common one.

One structured approach: Ultimate Campaign provides an abstract army-vs-army system with stat blocks, Offense checks, tactics, and resources. See the full Mass Combat rules →
Most tables handle war without any formal subsystem at all — and that is completely valid.

How Tables Actually Handle War

Most campaigns resolve mass conflict through one of these approaches. None requires a formal subsystem:

Narrative resolution
The GM decides the outcome based on story logic — who has better numbers, better position, a key advantage. PCs influence this through roleplay, negotiation, and key moments. No dice. Works best when war is backdrop, not the point.
Skill check resolution
One or a few opposed checks (Profession (soldier), Diplomacy, Knowledge (local/history)) represent the campaign, with PC actions providing modifiers. Fast, involves the whole table, scales well to a one-session war arc.
PC-scale encounters within the battle
The armies' outcome is predetermined or loosely tracked, and the real play is the PCs' mission during the battle — assassinate the commander, disable the siege weapons, hold the gate. PC success or failure shifts the war outcome.
Abstract stat-block system (UC)
The structured optional approach from Ultimate Campaign. Good if you want army-management as an ongoing campaign layer. Requires buy-in from the table and integrates best with the kingdom-building subsystem.

When the Formal Subsystem Helps

Works well when…
  • The party rules a kingdom and army management is already part of play
  • Players want strategic stakes — tactics, resources, commanders — as a game layer
  • The campaign has multiple wars across sessions, not a single climactic battle
  • PCs will command, not just influence, the armies
Skip it when…
  • War is a single dramatic moment in the campaign, not a recurring layer
  • The group isn't running kingdom building and has no BP economy
  • Only one player cares about the army rolls while others wait
  • The narrative outcome is already clear — the subsystem won't change it

Keeping PCs Engaged During a Battle

Regardless of which system (if any) you use to resolve the armies, the PCs should have something to do that matters.

  • Give them a personal mission. Assault the commander's position, destroy the ritual powering the undead, hold the gate against the flanking force. Make it a real encounter, not a side roll.
  • Make the battlefield visible. Narrate what the armies are doing while the PCs fight. Keep the scale present even if it isn't mechanically foregrounded.
  • Connect PC outcome to war outcome. PC victory: the army gains an advantage (+4 DV/OM if using the formal system, or a narrative edge if not). PC failure: they lose it.
  • Let spells matter at scale. Cloudkill, earthquake, control water are the moments armies remember. Reward the player who thinks at that scale.

Running a One-Session War Arc

1. Set the stakes
What changes if the players win? What happens if they lose? Keep it concrete and consequential.
2. PC mission first
Run the encounter the PCs can actually play. This is the session. The armies are context.
3. Resolve the armies
Use whatever method fits — narrative judgment, one check, or the full stat-block system. Apply PC result as a modifier.
4. Convert to hooks
Turn the outcome into campaign consequences: seized territory, routed enemy regrouping elsewhere, political fallout, wounded allies needing help.

Supporting Pages

If Using the Formal System
Campaign Context
OGL 1.0a Notice. Pathfinder-derived Open Game Content on this page is used under the Open Game License v1.0a and Section 15 notice.