Hi all, I have a player that is playing a level 3 cleric but is basing it around a plague doctor. The player has asked if his character could look into adding a feature to the mask he always wears to make it resistant to poison. All official magical items that give poison resistance appear to be rare which gives them a price tag of 501 - 5,000 GP if going off the DM's guide (Which is quite pricey) and really, he should be above level 5 before he gets the item. I know that I could turn around and just tell him all of this but from a more realistic approach, if he went to a tailor or leather worker with his mask and asked for some sort of filter to be installed then even in the real world, it wouldn't take too much to add some sort of filtration to a mask that is already designed to do something along those lines. It could take someone a long time to do it and he could be level 5 by the time it's done but it's going to cost quite a bit for what it is. On the other hand, I don't want to open the flood gates to the other players that will then think that they can also find someone to make them a personalised magical item. 

Thanks, Luke.

If you were going to do something like this, and want to keep it less-than-appealing for others to do something similar, you could make an item that has a similar effect as a magic item, but some kind of heavy restriction or consequence of using it. For a mask of poison resistance, maybe say that because it's not magical, it can only be used 'x' number of times before the filter needs to be changed, and the filter costs 'x' gold. This may even need to be made by some kind of specialist to get the mixture of filtration materials correctly. 

An alternative is to make them work for it :) Make it the end prize in an adventure quest, and let the Party know about it through some in-game means.

If you make the Adventure complex enough, he could be level 5 by the time he gets that mask, although - personally as a GM - I wouldn't sweat it too much if he got the item "early", especially if the Party had quested for it.

On the one hand, you're describing a head-slot Ring of Resistance, and there's no reason to give that out cheap. On the other, the magic item rarity spectrum can feel kinda whack and arbitrary. Giving the player advantage on saving throws against/resistance against poison damage from airborne poisons and gas is cool and fairly limited in scope.

I'd let him do it for 500 gp over 20 days, per the DMG downtime activities description. 

So for a filtration system like you are describing then the filter isnt permanent it has a limited use, so for one limitation though it gives him poison resistance from breatheable toxins (something you should stress, it doesnt protect from stingers or bites) it is only for a limited amount of time before he has to change the filter. The filter of course would likely not be cheap as it would have to be custom made or made by the player themselves with tinkering checks. Also if the filter runs out mid combat he has to decide whether to risk the poison or try and change the filter which you could apply a check to that as well.

It isn't quite what the player is asking for, but reflavoring a Necklace of Adaptation might be a decent alternative.  Especially if they do not want to need to spend thousands of gold making the item.

Hi all. Thanks for all of your advice. I really like the idea of the filter being the main point of this item and it having limited uses. The fact that it's not going to be all poison resistance and that it is limited to breathable gasses and vapors really lessens the value of the item but gives the player what they've asked for. As for leveling, I like the idea of it being someone special that has to make the item. If at the end of a quest the party rescues someone with the ability to craft such an item then it gives it as more of a reward to the party instead of an individual.

Thanks again for all of your help. Luke