Dr. Brawn is a rare human NPC in Palworld who can rewrite a single Pal’s IVs and Passive Skills once per in-game day. His experiment can add a coveted Rainbow Passive, but it can just as easily strip stats and stack negative traits, so the reward always comes with real risk.
Quick answer: Dr. Brawn spawns randomly at incident zones across the map. Put the Pal you want to modify in your active party, talk to him, and consent to the surgery. To use him repeatedly, capture him with high-tier spheres and place him at your base, where he runs one surgery per day-night cycle.

What Dr. Brawn’s surgery does
Once per in-game day, with a Pal active in your party, Dr. Brawn performs an experiment on it. The outcome is either positive or negative, and the result depends on the passives the Pal already carries.
| Outcome | Effect |
|---|---|
| Positive (Pal has 4 positive passives) | +15 IVs to all stats |
| Positive (Pal has room for a passive) | +15 IVs to all stats and adds a positive passive; a negative passive is replaced by a positive one first |
| Negative (Pal has 4 negative passives) | -30 IVs to all stats |
| Negative (Pal has room for a passive) | -30 IVs to all stats and adds a negative passive; a positive passive is replaced by a negative one first |
The added passive can include a Rainbow tier trait, which is the whole reason players seek him out. It will not roll exclusive passives such as Lucky, Legend, or the 20% and 30% elemental passives.
Note: A “successful” surgery still removes 30 points from the Pal’s base stats as a built-in cost. A Rainbow Passive offsets that penalty, but if the roll goes badly, you can end up with lower stats and a new negative trait like Easygoing.

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Dr. Brawn has a chance to appear at incident spots throughout the world map, similar to Black Market Sellers and Wandering Traders. His spawn is never guaranteed, so the reliable approach is to visit as many incident spawns as possible within a single in-game day. A fast-flying mount such as Jetragon makes the loop far quicker.
| Region | How to search it |
|---|---|
| Fort Ruins | Start at the Fort Ruins fast travel point and loop through the marked incident spawners before returning to the start. Repeat until he appears. |
| Feybreak’s Loess Plains | A single incident spawner. Check it periodically while you are on Feybreak Island. |
| Sakurajima’s Mushroom Wetlands | An event spot near a Predator Pal spawn. Visit it regularly for a chance to run into him. |
Tip: Mark every known incident point on your in-game map so you can sweep them in a set route. Fort Ruins tends to be the most consistent starting area.

How to run the surgery
You will know it worked when the Pal’s stat sheet updates. Check its IVs and Passive Skills afterward. A positive result shows higher IVs and a new beneficial passive, while a negative one shows reduced base stats and a new negative trait.

Capture Dr. Brawn to reuse him
Because his ability fires only once per day and finding him in the wild is slow, the most efficient method is to capture him. Like other human NPCs and Syndicate Thugs, he can be caught and kept at your base, where he stays put and can be used every day without another map-wide search.
His capture rate is extremely low, so bring the strongest spheres you have and expect it to take a long time. Ultimate Spheres are the practical choice, and even then you may burn through dozens of them before a catch lands. Once he is placed at your base, he performs one Pal surgery per Palworld day-night cycle.

Which Pals to put under the knife
Avoid using Dr. Brawn on a Pal you already value. The odds of a bad outcome are high, and a single failed surgery can leave a good Pal weaker for good, with both reduced base stats and a fresh negative trait.
The safer play is to target Pals that already carry poor passives, where the downside is limited. If a Pal has little left to lose, an experiment can only move it sideways or up, which makes it a much better candidate for a Rainbow Passive gamble.






