I actually converted a bunch of alchemical items in
ENWorld Arcana, which was supposed to be this giant collection of different people's houserules. Not sure what happened with that, but this is what I contributed:
Additional Alchemical Items
These variants improve on the base selection of alchemical items. I based all these items around the idea that a 50-GP single-use item should produce an effect roughly on par with a 1st-level spell (based on the numbers in the DMG). Alchemist's fire is grossly overpriced by that measure, so I made it better.
[sblock]
»Alchemist's Fire (revised): As described in the PHB, but on the turn it hits a target, it deals 1d8 fire damage immediately. The ongoing fire damage begins at the start of the target's turn, just like usual, but the damage is 1d6 each time instead of 1d4. (50 gp)
»Alchemist's Spark: Utilized like Fire variant, but deals 3d4 lightning damage on a hit. Also on a hit, all creatures within 5 feet of the target take the same amount of damage, or half as much on a successful DC 10 Dexterity saving throw. Creatures wearing armor made of metal have disadvantage on the save. (50 gp)
»Alchemist's Frost: Utilized like Fire variant, but deals 4d4 cold damage and slows the target for one minute on a hit. While slowed, all of target's speeds are reduced by 15 feet and any bonuses to speed are suppressed. It may end the effect early by using its action to successfully make a DC 10 Strength check. (50 gp)
»Thunderstone: Can be thrown at a point within 60 feet as an action, where it smashes. When smashed, all creatures within 10 feet of it take 1d10 thunder damage, or half that damage on a successful DC 10 Constitution saving throw. Any creature that fails the save is also deafened for 1 minute, or until they receive any magical healing. (50 gp)
»Aura Bomb: A flask of luminous swamp gas and ground foxfire. As an action, throw it at a point within 60 feet to outline everything within 10 feet in harmless ghostly flames. All objects in the area, as well as creatures in the area that fail a DC 10 Dexterity saving throw, are affected as if by the
faerie fire spell, but the effect is not magical and only lasts until the end of your next turn. (40 gp)
»Fortifying Tincture: This is a simple herbal tonic designed to improve one aspect of your physical capabilities for 10 minutes after drinking. A fortifying tincture can be brewed to boost either Strength, Dexterity, or Constitution. While under its effects, whenever you make a saving throw or ability check with the designated ability, you roll a d4 and add it to the d20 roll. Drinking another tincture while still under the effects of a previous one will cause the previous one's effects to end early. This concoction can be brewed with either alchemist's supplies or an herbalism kit. (30 gp)
»Smokestick: As an action, you can snap the end off this short, wooden rod to spark an alchemical reaction. When broken, thick, gray smoke billows steadily out of it, heavily obscuring the area within a 10-foot radius in a matter of seconds. The smoke doesn't rise or sink, but it disperses on its own after 1 minute. Moderately fast wind (at least 10 mph) disperses the cloud early. The stick is too light to be thrown farther than 20 feet on its own. (20 gp)
[/sblock]
Additional Rules involving alchemical items:
This variant adds extra items for alchemist's supplies to craft, a way to boost their power at higher levels, and a few other things.
[sblock]
»Like all improvised weapons, alchemical weapons requiring attack rolls can also be thrown as far away as 60 feet, but aiming at anything further away than 20 feet imposes disadvantage on the attack roll.
»Increase the DCs of saving throws and ability checks called for by alchemical items by the Intelligence modifier of the creator. +2 or +3 is a typical amount for alchemists selling their wares.
»It would be historically accurate to add the following to the list of things a character proficient in alchemist's supplies can craft: fine inks (of a high enough quality to be suitable for magical procedures), gunpowder (said to be discovered by Chinese alchemists), and holy water (most alchemists held a very religious view of their ancient science; the quest to transmute lead into gold was viewed by most as a metaphor for the purification of the soul, believing any physical refinement could also be duplicated spiritually).
»When crafting an alchemical item, a character makes progress in increments of 25 gp per day, as if it were a magic item. It still only costs half the base price in raw materials.
»A character proficient with alchemist's supplies can attempt to empower any alchemical item by very carefully fusing the essences of two identical items into a single compound. Doing so requires an hour of work and a successful DC 16 Intelligence check. On a failure, both items are ruined. On a success, the item's potency increases twofold. All attack rolls, saving throws, and ability checks still occur as normal, but any effects that occur as the result of a roll are applied twice. In addition, the DC for any saving throw or ability check the new item calls for is equal to the higher of the two combined items' DCs, plus two (for example, combining a DC 11 item and a DC 13 item will create a DC 15 item). An already-empowered alchemical item cannot be empowered again.
[/sblock]
