Using This Overlay

Open the PHB to a section. Open the PHBO to the corresponding section. The status marker at the top of the PHBO entry tells you immediately what to expect — whether the PHB rule applies as written, whether it has been changed, whether it has been replaced entirely, or whether it does not apply in Oath-Bound at all. The Legend explains each marker in full.

In most cases the marker is sufficient. An entry means the PHB section applies without modification. There is nothing further to do. The PHBO may add a brief note where context is useful, but if the rule stands as written, the overlay gets out of your way.

Where a rule has changed, the PHBO explains what changed and why. For significant changes, it links to the Oath-Bound Rules Module (CRM) — the live rules document — where the full replacement treatment lives.

The PHBO does not reproduce PHB content. It references it. Section headings appear as navigation anchors; the content beneath them is Oath-Bound-specific commentary, not a restatement of the original. You need the PHB to use the PHBO — that is deliberate and will not change.

That said, the changes that affect character creation and everyday play are explained here in enough detail that a player who reads the relevant PHBO sections carefully can build and run an Oath-Bound character without having the PHB in front of them at all times.

The CRM — the Oath-Bound Rules Module — is the full live ruleset. It is primarily a GM-facing document, but players will occasionally be pointed toward it for rules that replace PHB content in ways that go beyond a brief overlay note. Those cross-references appear where they are needed. You do not need to read the CRM in advance.

The PHBO is a living document. Sections that have not yet been reviewed carry the marker. A pending section should be treated as applicable as written until a status is assigned.

The Preface covers the most significant departures from vanilla AD&D that a player will encounter — alignment, divine characters, dice resolution, advancement. It is worth reading before anything else, particularly if you are new to Oath-Bound.

The Legend explains the marker system. Read it before working through any section of the overlay — the markers appear on every page and their meaning should be clear before you encounter them in context.

After that, the PHBO does not need to be read linearly. Character creation in Oath-Bound is undertaken at Session Zero — a group process, not a solitary one — so the sections most relevant to building your character are best encountered there, with the GM and the rest of the table present. Work through the rest as questions arise in play.