Grim Arithmetic is a Pathfinder Second Edition GM utility for Foundry VTT that estimates short-term danger for your party. The core Encounter Danger Board reads active combat tokens and shows pairwise immediate down-risk for every PC versus every hostile enemy, with a Pair Detail popup for deeper lookups on individual strikes. You can also use the traditional select-PC-and-target-enemy workflow for focused analysis.
The new Forecast panel runs a encounter simulation to project outcomes over multiple rounds. Pick from five tactics profiles (Spread Damage, Focus Fire, Predator, Boss Cinematic, or Random Legal), then run to see headline metrics: Any PC down, TPK risk, and Expected first down. This is combined with per-PC breakdowns and 95% confidence intervals. PCs now act in the simulation with Strikes, healing (Battle Medicine, Heal Spells & cantrips), recovery checks, and Hero Point death prevention, giving the GM a much more realistic picture of encounter difficulty.
It is intended as a table aid for quick tactical awareness and encounter planning, not as a full combat simulator or permanent-death predictor. Grim Arithmetic currently models supported PF2e actor data including Strike damage, resistance/weakness/immunity adjustments, and the PC survival mechanics described above.