I am an alchemist level 10, and I used Malignant Poison on my Black Lotus Extract so it has DC 24 and takes two consecutive saves to end.
When I affected an enemy with it, my GM succeeded the 1st save and failed the other one. However he didn't agree to take the poison damage because “it doesn't make sense that it has two saves.”
This is clearly not following the rules for Black Lotus Extract. How do I convince the GM that it should work the way it says it works?
As a full-round action, the alchemist can increase the save DC of any poison by 4 and increase its duration by 2 frequency increments (for example, large scorpion venom lasts 8 rounds instead of 6 and drow poison lasts 4 minutes instead of 2). Additionally, malignant poisons take effect immediately and do not have an onset time. This alchemical change lasts until the poison's extended duration ends or for a number of minutes equal to the alchemist's level, whichever comes first. After that, the poison reverts back to its original state.
Type poison (contact); Save Fortitude DC 20
Onset 1 minute; Frequency 1/round for 6 rounds
Effect 1d6 Con damage; Cure 2 consecutive saves
So based on the rules as written, The save of the poison would be DC24, it would last a total of 8 rounds instead of six, doesn't have an onset time, and stays this way until a number of minutes equal to the alchemist level, after which it turns back into a regular poison.
In order to cure the poison Black Lotus extract requires two consecutive saves. If someone affected by it makes the first but fails the second, the poison stays in effect until they make both saves consecutively.
You need to talk to your GM and explain your reasoning behind taking Malignant poison, tell him your intentions, what it does, and how poison works as a whole. Show him poisons that have similar statuses and also require two saves. You should also mention that if you knew how he was initially going to treat poison and that he wasn't going to follow the rules as written that you likely would have never chosen the ability to amplify poison in the first place.
If he considers all this one of two things will happen, he'll either let you re-choose another alchemist discovery and play will proceed on from there or he'll use poisons correctly and from that point on anytime you use such an expensive poison that does have multiple saves as its cure condition he'll be aware of its usage and can compensate during play.
Your GM was right... technically... and depending on the details.
And he was right for a reason other than the one he gave.
Your explanation of the situation could be interpreted in two ways. When you say:
"When I affected an enemy with it, my GM succeeded the 1st save"
...if you meant the enemy had already failed a save before the GM made his 1st save, then you are correct. If the enemy had not saved yet, then he is correct.
The rules for poisons are pretty complex and don't provide a lot of explanation. There's a detail about them that isn't intuitive: even if a poison, or any affliction for that matter, requires more than one save to cure, you still resist all of the effects of a poison on the first save.
For example, your Black Lotus Extract requires two saves to cure. Once afflicted, a victim rolls a fortitude save to resist the poison. If he succeeds, he's done. Not afflicted whatsoever. No more saves.
If however, he fails his first save, he will then have to make two additional successful saves in a row to cure the affliction.
The rules for poisons and afflictions cover this, although not clearly. There is a summary at the bottom of the poison's page that covers this detail, however.
I'd say to point your GM to the OGC. If he disagrees then at that point it's a house rule and you'll have to solve the issue through social channels.
The DM is in his right to say that, but he should discuss it with you or make it clear that this kind of house rule exists beforehand
That said, did he specify why it "doesn't make sense"? The poison having 2 saving throws serves to make it harder to resist, so it actually does make sense that those two dice rolls are in place.
To directly answer your question: Ask him.
I, personally, would talk to the gm and see why he thinks that it doesn't make sense. Maybe he has a good explanation, or maybe he just did not want the particular target to be poisoned (if that is the case, this might not have been the best way to achieve that, to be honest)
Sure, he as a GM gets to make the rules, but he gets to make them for all of you (including him, btw!) to have fun.
It is a bit unclear what do you mean by the word "affected".
In this case his NPC's first save would be to not be poisoned at all. He doesn't need to make more than that one save no matter what type of poison you use.
Check the bottom of this page for "How Do Poisons Work?" summary.
But if his NPC failed initial save to be poisoned (being in your case also the first save to resist) in the first place and thus was "affected", then it is another case. If after that he made his next save (wich you reffer to by "first"?) to resist poison effects, he definitely must succeed on another save in a row to shake off (cure) poison allready affecting him.
