The Homebrew System
How Mimir handles custom content and why it works the way it does.
Why Homebrew?
The D&D 5e catalog covers thousands of items, monsters, and spells — but every DM eventually needs something custom. A magic sword with unique properties, a modified monster, a spell variant. Mimir’s homebrew system lets you create and manage these alongside official content.
Campaign-Scoped
Homebrew content belongs to a specific campaign. This is intentional:
- A magic sword in your “Curse of Strahd” campaign doesn’t clutter “Tomb of Annihilation”
- Different campaigns can have different homebrew with the same name
- Exporting a campaign includes all its homebrew
Three Content Types
Items
The most flexible type. Items can be created from scratch with a structured form (name, type, rarity, weight, value, description) or cloned from the catalog. Weapon and armor types get additional fields for damage, AC, and properties.
Monsters
Created by cloning from the catalog only — there’s no blank monster form. This is because monster stat blocks are complex JSON structures. Clone an existing monster and modify its data to create your variant.
Spells
Same as monsters: clone-only. Spell data is structured JSON, so cloning provides a valid starting point that you can modify.
Clone from Catalog
The clone workflow is the heart of the homebrew system. Rather than starting from a blank form, you find a similar catalog entry and clone it — Mimir creates a homebrew copy immediately, ready to edit, and the copy remembers its origin (“Based on [original name]”).
This approach is faster than creating from scratch and ensures the data structure is valid: a cloned monster or spell is guaranteed to have a well-formed stat block, because it started as one. For the step-by-step procedure, see Create a Homebrew Item.
Integration Points
Homebrew content isn’t isolated — it flows into the rest of Mimir:
- Items appear in character inventory search results when adding equipment
- Monsters appear in Token Setup when placing tokens on maps
- Spells appear in character spell lists for spellcasting classes
All homebrew entries are tagged with an HB badge so you can distinguish them from catalog content at a glance.
Data Storage
Homebrew content is stored in the campaign database alongside catalog data. Items use structured fields (name, type, rarity, etc.) while monsters and spells store their full stat blocks as JSON. This means:
- Items have a user-friendly form editor
- Monsters and spells use a JSON text editor
- All three types support the clone-from-catalog workflow