Warlock Chain Poison Harvesting

Simple non broken Homebrew to present to your DM 

Pact of the chain Warlock only

Familiar toxin milking:

Once per long rest Warlock may make a DC 15 (nature) poison harvesting check (because your familiar is indeed a willing celestial/fey/fiend) 

If the check is successful roll 1d4 the result equals the amount of doses milked, these doses can be applied to weapon or ammunition as a bonus action, once applied in this fashion the toxin is expended after 1 minute or after a successful attack with that weapon or piece of ammunition, any remaining unapplied doses milked become inert after 24 hours.