Warlock Chain Poison Harvesting

Nowhere in there does it explicitly say that you cannot extract poison from a creature that is still alive, this is a familiar we're talking about, one you can communicate with. It would be just like a biologist harvesting venom from a snake. Especially if you communicate with the familiar and ensure it is okay with the practice, and ensure that it is done in a safe sustainable manner. 

:3

A character can attempt to harvest poison from a venomous creature that is dead or has the Incapacitated condition. 

It does not allow you to coax poison from your familiar.  RAW it has to be dead or incapacitated.  As noted elsewhere this means you can harvest from your familiar and then dismiss it and resummon to get a new one.  That comes with some GP cost and you do save money, but it is not free.  The only way I see to do it mechanically is Feign Death.  If someone has a better way to get 6 minutes of incapacitated on your familiar I am all ears.

Quote from Elfdope >>

If someone has a better way to get 6 minutes of incapacitated on your familiar I am all ears.

 I feel like just commanding it to go to sleep is a pretty straightforward way to do this.

Commanding it to sleep.  Interesting approach.  I had forgotten Unconscious got you to incapacitated.  Will still require some DM approval, but it would seem fine to me.

Quote from Elfdope >>

Will still require some DM approval, but it would seem fine to me.

I feel like if you can get your DM to agree to all this poison-harvesting stuff at all, getting them to allow you to tell your familiar to take a nap is probably a much easier sell.

• It Is Willingly Coordinated: The "dead or incapacitated" clause exists because a wild, dangerous monster will bite your face off if you try to squeeze its venom glands. Your pseudodragon familiar is a magically summoned spirit completely loyal to you. It wants to cooperate.
• "Milking" vs. "Harvesting": In the real world, you don't kill a snake to get its venom; you gently milk it into a jar. Because your familiar complies, the "incapacitated" requirement is narratively bypassed because it is voluntarily holding still.
• It’s Not a Real Pseudodragon: Per the Find Familiar spell, your companion is actually a Celestial, Fey, or Fiendish spirit taking the form of a pseudodragon. If it "dies," you don't get a corpse—it vanishes into mist and you just spend 10 gold pieces to resummon it perfectly intact. [1, 2, 3, 4, 5]

1. Lower the DC for Willing Targets: Suggest that because the pseudodragon is completely willing and sitting perfectly still, the harvesting check drops from a DC 20 down to a DC 12 or 15.
2. Enforce Tool Proficiency: Require a Poisoner's Kit check rather than standard Nature. This represents the chemical know-how needed to stabilize the venom so it doesn't evaporate or go inert immediately.
3. Implement a Cooldown (The "Gland" Limit): Limit the harvesting to once per Long Rest. A pseudodragon's body can only produce so much venom naturally. Resummoning the familiar shouldn't reset this, as it's the same spirit tethered to your magic.
4. Risk of Failure: If you fail the tool check by 5 or more, the familiar accidently pricks you, forcing you to make the saving throw against its poison. [1, 2, 4, 5]