How to extract
Each poison has a certain DC that decides whether it works or not. To extract a poison, the character has to have a Poisoner’s kit and spend a number of minutes equal to the poison’s DC uninterruptedly extracting it. The character has to pass a Nature check against the poison’s DC to successfully extract it. If the character is proficient with the kit, the character’s proficiency modifier may be added. If the character fails the check by 5 or more, the character is subjected to the poison’s effect.
|Assasin’s blood||Ingested||DC 10|
|Basic Poison||Injury||DC 10|
|Serpent venom||Injury||DC 11|
|Truth serum||Ingested||DC 11|
|Burnt othur fumes||Inhaled||DC 13|
|Carrion crawler mucus||Contact||DC 13|
|Drow poison||Injury||DC 13|
|Oil of taggit||Contact||DC 13|
|Wyvern poison||Injury||DC 15|
|Essence of ether||Inhaled||DC 15|
|Pale tincture||Ingested||DC 16|
|Midnight tears||Ingested||DC 17|
|Purple worm poison||Injury||DC 19|
For more details (with lower rule priority for me) on the poison, see this link.