D&D PvP: How to balance one powerful vs two weaker players.

Quote from heydanseegil >>

Alchemist make potions and they can be built to craft them three times as fast with the right Feats. Once they have at least 41 hit points you can begin experimenting on yourself using Miscibility which makes the effects of a potion permanent on a 100

Bear in mind that a character under the influence of a permanent potion will have to roll potion miscibility every time they drink a potion (potion miscibility applies if you drink a potion while under the effects of another potion. Nothing says that permanent potions are an exception). Since this will delete both potions on a roll of 1-25, good luck getting more than one effect.

Quote from heydanseegil >>

Quote from The_Ace_of_Rogues >>

… How exactly is an Alchemist Artificer so fundamentally broken?

Shoot I meant to reply to this. While it may not be as helpful in a PvP immediately upon making the character it will if the character has significant down time.

Alchemist make potions and they can be built to craft them three times as fast with the right Feats. Once they have at least 41 hit points you can begin experimenting on yourself using Miscibility which makes the effects of a potion permanent on a 100, couple that with the Human feature that provides the Heroic Inspiration and you can make two rolls on the Miscibility table turning that chance into a 1 in 50 from a 1 in 100. Start drinking two Elixirs of Resilience at the same time every chance you get and each time you gain the permanent benefit it not only stacks but has to be individually dispelled.

I got my Alchemist to AC 30 from AC 10 in under a year of downtime but you can do other stuff too like give yourself permanent dragon breath or whatever. The only draw back is the amount of prep time makes it impractical in most campaigns but if I get the down time and I have more than 40hp to survive the damage if I get a 1 on the Miscibility roll then I start experimenting with chemistry.

As Pantagruel666 already said, anything can be broken if you ignore the rules.  You are ignoring several rules here:

1. The Miscibility table only applies to potions.  Elixirs are similar to potions, but they are based on a class feature and not actually potions--they do not use the word "potion" anywhere in their rules.  This is intentional, given potions have specific rules.  Accordingly, the miscibility table is not applicable. 

2. Even if it were a potion, you cannot stack magical abilities of the same name, and thus cannot be under the effect of two Elixirs of Resistance at the same time.  This is a fundamental, core part of the D&D rules.

3. Even if it were a potion and could be stacked, any time you drink a new potion, you would have to roll again and could lose both effects.  (Edit: Looks like  Pantagruel666 said this above as well).

So, no, this does not work, and if it did work, it still would not work, and if it did work both ways, it would not practically work for a third reason. 

____

Going back to the actual thread, since the above is a distraction without basis in rules, I have DMed a lot of PvP in D&D - almost always because it is worked into the story (ex. players under the effect of mental magic). I agree with others have said about PvP being unbalanced.  Others have already extensively touched on why this is - nova potential, battlefield changing skills, player skill (both at combat and just designing their character), and, of course, pure, dumb luck.  

Here is the one thing I do not think has been said on this thread yet... PvP can be a lot of fun, but it should be used only when absolutely necessary to increase the entertainment of the party.  Lots of players secretly wonder "would I win?" and it can be very fun to let people live out that fantasy in a controlled environment. 

But I have to put the stress on controlled environment.  This is a situation where (a) every player involved in the PvP (above table) is comfortable with the arrangement and (b) there are not going to be long-term feel bad consequences to something that is inherently unbalanced and thus not overly fair.  For example, a one-shot heist, where everyone knows it might go full Reservoir Dogs at the end, would meet both requirements - everyone knows what they are getting into when they sign onto the game and it is a one-shot, so there are no long-term consequences.  A friendly duel where the players are under the effect of a death ward?  Also makes sense.   As with most things in D&D, knowing what your group enjoys and can tolerate is a good idea - and if there is any uncertainty, it might be wise to put the game on a brief pause for an above-the-table discussion before PvP starts. 

But someone trying to kill another player permanently because of in-character disputes?  Bad, bad idea, except in a very rare type of group. 

I would love to see OP respond and explain why they are doing this, as others have asked, so more specific feedback on their situation can be provided.  

(Note, this is not PvDM with PvP elements, such as when a player is dominated by a monster.  That is not really PvP - that is PvDM where an enemy is wielding the player, and is evaluated differently).  

I mean it is in the DMG but I wouldn't say it is abusive. At least not anymore so than using anything else in the DMG as a player such as creating an environmental effect or building and using siege equipment which is definitely something I could see an Artillerist doing. Them the rules of the game after all.

However, I can understand your fear and so I might suggest either not giving your players enough downtime to make such a feat possible (our DM did but we also faced all the demons from Out of the Abyss at the same time inadvertently saving Menzoberranzan) or you could make the process have a more severe draw back. I would do this as a DM by making one of the Complications during crafting creates a flaw in the brew turning it into a narcotic like Tanasbra in the case of a Healing Potion. Then the alchemical abuse has both a mechanical and thematic impact to the game.

Actually, I made a minor mistake. It's not difficult to be under the effects of two permanent potions, it's completely impossible, because a 00 result causes one effect to be permanent and the other effect to be removed, and thus any time you gain a permanent effect the prior effect will be removed.

Quote from Pantagruel666 >>

Actually, I made a minor mistake. It's not difficult to be under the effects of two permanent potions, it's completely impossible, because a 00 result causes one effect to be permanent and the other effect to be removed, and thus any time you gain a permanent effect the prior effect will be removed.

That isn't what Miscibility reads. You drink two potions and keep one of their effects permanently. You don't lose the effects of any other. No where does it read you lose any effect of any potion. The only way to remove any effect gained this way is through Dispell Magic and it even reads that is discretionary not a hard ruling. So, Dispel Magic may not even work and even then it reads 'this' effect indicating only one effect at a time may be removed in this fashion.

They want us to experiment on ourselves and the party. It is the strongest ability an Alchemist brings to the table. Permanent, possibly unremovable, spell like effects; but it does take a lot of preparation work and a high enough level to have the HP to survive a 1 on that roll.