What is the D&D 5.5e Bastion System?

The Bastion system is an optional downtime ruleset introduced in the Dungeon Master's Guide for Dungeons & Dragons 5.5e (the 2024 revision of D&D 5e). Starting at character level 5, a player character can establish a bastion — a personal stronghold built from modular facilities, run between adventures through structured bastion turns that produce resources, advance projects, and trigger random events. It turns the time between dungeons into a real, mechanically meaningful part of the game.

BastionForge is a free mobile companion app for iOS and Android that handles the bookkeeping for you so the table can focus on the story.

A bastion is built from two kinds of facilities:

• Special facilities are the unique rooms that define what the bastion does: a Sanctuary, a Workshop, a Library, a Garden, a Sacristy, a Trophy Room, and so on. New special facilities unlock as the character gains levels (typically at levels 5, 9, 13, and 17).
• Basic facilities are the supporting rooms that fill out the bastion's size: bedrooms, kitchens, storage, courtyards, parlors, stables. The number of basic facilities a character can have is determined by the bastion's overall size, which scales from Cramped at level 5 up to Vast at higher tiers.

Each facility has a condition — operational, damaged, destroyed, upgrading, or under construction — and most have a hireling who staffs them. Conditions change over time as a result of bastion turns and events.

A bastion turn is the unit of downtime that drives the system. By default, one bastion turn passes for every 7 in-game days spent away from the bastion (DMs can adjust the cadence to fit their campaign). On each turn, the player issues an order to every operational facility:

• Recruit — gain followers, a small army, or a specialist.
• Craft — produce mundane goods, magic items, or potions, depending on the facility.
• Trade — convert goods into gold or negotiate favors.
• Empower — bind a temporary boon to an item or character.
• Harvest — gather a renewable resource the facility produces.
• Maintain — keep the facility in good repair and the hireling content.
• Research — learn lore, secrets, or names relevant to the campaign.

Not every order is available at every facility — a Garden harvests, a Workshop crafts, a Library researches. Each order has its own inputs, dice rolls, level gates, and outputs, which is exactly the kind of bookkeeping that's tedious to track on paper across an entire campaign.

At the end of each bastion turn, the DM rolls on the official d100 Bastion Events table. The result might be a friendly visitor, a magical phenomenon, a discovery, a mundane occurrence, or — in the unlucky cases — an attack on the bastion itself. Events can damage facilities, present roleplay hooks, or unlock new opportunities for the next session.

The event table is what makes the Bastion system feel alive. It also produces a lot of one-off rulings and consequences that need to be remembered weeks or months later — another place where a digital tracker pays for itself.

The Bastion system rewards consistent, long-term play. A campaign that runs for a year of real-world time can produce 30 or more bastion turns per character, each with multiple orders, dice rolls, condition changes, and event outcomes. Multiply that by a party of four or five players, each with their own bastion, and the bookkeeping quickly becomes the largest single tracking task at the table.

Spreadsheets work, but they don't enforce the rules, don't remember the exact 2024-edition order inputs, and don't roll dice. A purpose-built tool does.

BastionForge is a free companion app for iOS and Android that handles every part of the Bastion loop:

• Build the bastion. Pick from 33+ official facilities. The app enforces level gates and bastion-size caps automatically.
• Run a turn in three steps. A guided wizard walks the player through issuing an order to every facility, rolling the d100 event, and reviewing a turn summary.
• Roll the official event table. Color-coded outcomes and a full event journal so nothing gets lost between sessions.
• Co-owned bastions. An entire party can share and manage one stronghold. Each player can issue orders; everyone sees the results.
• DM tools. Dungeon Masters host campaigns with a 12-character invite code, see every player's bastion at a glance, and can homebrew custom facilities with their own orders, dice rolls, and rules.
• Offline at the table. 24-hour cache so the app keeps working when the venue's WiFi doesn't.

BastionForge has a free tier that's enough for a full campaign (1 campaign, 1 bastion, 4 players, 1 custom facility) and a Premium subscription that unlocks unlimited everything, full turn history, and premium content packs.

• DMs running 2024-rules campaigns who want to keep player downtime engaging without becoming the bookkeeper for everyone's stronghold.
• Players whose characters reach level 5 in the new ruleset and earn their first bastion.
• Tables transitioning from D&D 5e to D&D 5.5e who are adopting the Bastion system as one of the new optional rules.

BastionForge is free to download. Join the waitlist on the homepage to be notified when the app launches on the App Store and Google Play, or jump to the full feature list to see what's included.

BastionForge is an independent fan-made companion app. It is not affiliated with, endorsed by, or sponsored by Wizards of the Coast LLC. Dungeons & Dragons is a trademark of Wizards of the Coast LLC. The Bastion system is described in the 2024 Dungeon Master's Guide.