It is needed to craft the following items:
Acid extract is required to craft enriched dimeritium ore which is required to craft grandmaster witcher gear sets.
- The best source for acid extract are giant centipedes, as they do not only drop the extract itself, but also giant centipede discharges and giant centipede mandibles, which when dismantled yield two acid extract. Thus one centipede kill will yield around ten acid extract.
- Killing kikimores may drop kikimore discharges, which can be dismantled for three acid extract each.
- Even with a fully patched game, some players may run into a bug where none of the monster parts can be dismantled for acid extract. If that's the case, then most likely archespore tendril can drop acid extract instead (other cases, it's supposed to drop venom extract).