System Conversion Notes

Every recommendation is a starting point, offered so a GM does not have to invent a ruling from nothing on the first session. Nothing here is binding on the fiction. If your table finds a better mechanical home for an idea, the idea, not the mechanic, is the part of tThis book that matters.

None of these three systems is the correct choice. 5e is the system most tables already own. Pathfinder 2e is built for tactical precision and genre-flavored magic traditions. Blades in the Dark's native stress-and-bond economy already resembles this setting's themes more closely than anything you could bolt on.

Maps a Mar de Oro Calling to a class or playbook in each system. Use it to get a character to the table quickly, then let play pull them off the path.

The Powered Arts are cultures atop one reality; each system already has a natural home for their temperaments.

Reflavor Wild Magic Sorcery so its table draws from Fortera instability rather than chaos magic. Fortera strain past what local replenishment can support is one level of Exhaustion, not simply a spent slot.

Inert Éterlumin is cargo; the semi-state is a hazardous environment requiring Constitution saves; the active state uses existing flammable-object and explosion rules, reflavored.

Award Inspiration when a player honors a Bond at real cost, and treat an unresolved Burden as a standing complication the GM is entitled to bring back.

The three-action turn is a genuinely good home for Overdraw decisions: let a fourth, unsafe action exist outside the normal three, available only by accepting Fortera strain or Éterlumin exposure.

Overdraw applies the Drained condition, recoverable on a full night's rest in a stable location. Build semi-state Éterlumin as a statted hazard.

A written Bond grants a +1 circumstance bonus once per session when the character acts to protect or honor it; a Burden may be spent by the GM to introduce a complication in exchange for a Hero Point.

Bonds, Stress, and Trauma are core mechanics rather than optional flavor, so a Mar de Oro campaign generates this book's central themes automatically. Build a custom crew type, a Golden Sea Company, alongside the existing sheets, with upgrades drawn from the continental powers and denominations.

Treat Fortera access as a special ability available to any playbook, gated behind a Whisper-style ritual list reflavored across all five traditions. Overdrawing Fortera marks stress directly. Exposure to semi-state Éterlumin is a natural trigger for a Devil's Bargain. Burdens are Trauma conditions given a specific in-fiction source the GM should always be prepared to name.

Naval action: treat a ship the way tThis book treats a character, with a Bond to its crew and a Burden it is still carrying. Track Hull, Rigging or Lift, Crew, and, for airships, Éterlumin Reserve. Abstract range into four bands - Distant, Closing, Engaged, Grappled. Boarding actions can only be declared from Grappled.

Wounds and lasting injury: whenever a character is dropped to zero, record a Lasting Injury - a scar that aches before storms, a hand that no longer holds a line steady, a lung that never fully cleared. Mechanically small, narratively permanent. Death should be earned, not accidental. Fortera-based revival should exist in the fiction as a genuine miracle, not a spell on a list: rare, visible, and costly.

Repair under pressure: treat a broken machine as an adversary. Give it a Repair track a few successes long. Each success fills the track; each failure introduces a new complication - a second rupture opens, a fire spreads, a valve jams, water rises, the resonance climbs another step. A tool, not a tax. Reach for it only when the fiction is already tense.

When a player wants to use Fortera, ask one question before you ask for a roll: is this draw within what local replenishment can support, or is it an Overdraw? Ordinary use costs nothing beyond the system's normal resource. An Overdraw is a deliberate push past that.

An Overdraw should always do two things at once: give the character something they could not otherwise have, and cost them through the Fortera strain mechanic. If the working happens near active or semi-state Éterlumin, add the relevant hazard on top rather than in place of the strain cost.

For every two muskets firing in unison, add 1d10 to the damage pool, capped by target size. Dexterity save DC = 12 + 1 per 5 shooters (max 18); success halves. Wisdom save at the same DC or be Suppressed until the end of the target's next turn (half movement, disadvantage on attacks). Morale save at DC 12 if a formation loses more than half its HP to one volley. A formation needs one round preparing and one reloading between volleys and cannot volley while Suppressed.

Constitution save at DC = 10 + (2 × tiers over capacity). On a failure the character suffers the severity below and warps the local field.

Use these when a table wants ship combat resolved in hit points and broadside dice rather than tracks and bands. All listed vessels are immune to small-arms fire; only cannon, siege weapons, Fortera workings, and other ships threaten them.

Signature traits distinguish the doctrines. The Valdegracian Justicar suppresses everything in its line of fire (DC 15 Dexterity) and anchors allied vessels with +1 AC. Albionis vessels trade armor for initiative and precision. Duchy of Heller designs are the innovators: steam boosts, vector drives, and a Tender that repairs 3d10 and recharges Éterlumin systems.

Rather than only whittling total hit points, a called shot can cripple a system. Divide a ship's HP into five subsystems by percentage; reduce one to zero to disable that function while the hull fights on.

If your table already has a system it loves, use these notes to graft Mar de Oro onto it rather than switching systems to fit the setting. The setting was written to survive the graft.

If your table is choosing fresh and has no strong preference, Blades in the Dark will ask the least of you and give back the most in mechanical alignment with what tThis book is actually about.