Despite the misleading description, this attribute is triggered by high toxicity not by poisoning. And this can be demonstrated in this way:
- Allocate your talent to Altered metabolism (under 4th level Stamina).
- Elevate Geralt's toxicity, by drinking several normal potions then make some "failed potions" (the idea being that you want to drink something very toxic and the effects are more or less random, so have a few and save!).
- A Potion mix that could potentially Poison Geralt is the Cat Potion, with Vinegar added as the 4th ingredient. Cat Potion only uses 3 reagents to mix (potion base excluding) the 4th slot is open, this is the slot in which the vinegar reagent should be added.
- Swig each of these potions in turn until Geralt's toxicity is at least 51.
- Now drink something you know is poisoned. (The yellowy-green critical effect icon — — which normally indicates poison does not appear on the ring around the medallion).
This has also been tested and found to work in fights where the opponent uses Pain, like the striga.