Harbinger of Doom

D&D 5e: Alchemical Experimentation

I've created two different types of alchemical experimentation, to account for the gameplay difference between adventuring time and the downtime that precedes an adventure. To put that another way, damage matters if you're taking a long rest in the course of adventuring, but not if you're taking a few days or weeks of downtime. Stories about alchemists dying to catastrophic explosions are valid, but probably not an interesting risk for PCs to take during downtime. (This is basically the same as "a PC never dies off-camera.")

The first table is for use as part of any long rest. This action is open to any character with an alchemist's supplies or similar equipment. Roll d100 and add your level; if you are an Alchemist (per the subclass, the Guild Artisan background, third-party class, feat, or whatever else the DM rules sufficient), add twice your level instead. At the DM's discretion, you may be able to expend alchemical reagents as well, granting an ad hoc bonus to your roll. You may forgo some or all of your bonus from level if you wish.

d100+level

Result

1-20

Toxic Gases. All creatures within 30 feet roll a DC 10 Constitution saving throw. On failure, take 1d10+your level poison damage. On a success, the first Con save they roll before their next long rest gains advantage.

21-30

Minor Explosion. Roll a DC 12 Dexterity saving throw. On a failure, you take 1d10+your level fire damage. On a success, the first time you deal fire damage before your next long rest, you may reroll all 1s for damage, keeping the new result.

31-40

Strange Fumes. Roll a DC 12 Wisdom saving throw. On a failure, you take psychic damage equal to your level. On a success, you gain telepathy, 30-ft range, until your next long rest.

41-50

Mutagenic Vapors. Roll a DC 13 Constitution saving throw. On a failure, your speed is reduced by 10 feet and you suffer disadvantage on all Strength saving throws until you complete a long rest. On a success, your speed is increased by 10 feet and you gain advantage on all Strength saving throws until you complete a long rest.

51-60

Destructive Explosion. Roll a DC 13 Dexterity saving throw. On a failure, you take 1d10+your level fire damage, and one piece of useful gear weighing 1 lb. or more is destroyed. On a success, you gain resistance to fire damage until you complete a long rest.

61-70

Acid Burst. Roll a DC 14 Dexterity saving throw. On a failure, you take 1d10+your level acid damage. On a success, you gain resistance to acid damage until you complete a long rest.

71-80

Thunderstone. All creatures within 60 feet roll a DC 14 Constitution saving throw. On failure, they are deafened for 1d6 hours. On a success, they gain resistance to thunder damage for 1d6 hours.

81-90

Wild Insight. Roll a DC 15 Intelligence saving throw. On a failure, no effect. On a success, double your available spell slots for one level of spells that you cast until you complete a long rest.

91-100

Magical Interference. Roll a DC 20 Intelligence (Arcana) check. On a failure, magical healing is half as effective on you until you complete a long rest. On a success, gain advantage on saving throws against spells for 1d6 hours.

101-110

Coughing Fit. Roll a DC 16 Constitution saving throw. On failure, you automatically fail Dexterity (Stealth) checks until you complete a long rest. On a success, you can spit acid as a ranged attack at a target within 30 feet, using a bonus action. On a hit, deal 2d6 + your Dex modifier acid damage. This benefit lasts until your next long rest.

111-120

Refiner's Fire. You may choose to destroy 1d6 pieces of gear worth 5 gp or more. If you do, the next weapon, arcane focus, shield, or suit of armor you touch gains a magical +2 bonus to attack and damage rolls for 8 hours.

121+

Chrysopoeia. You transmute base materials into gold, creating 4d20 x 5 gp.

d100+level

Result

1-20

Toxic Gases. Roll a DC 12 Intelligence saving throw. On failure, all vegetation within 120 ft. withers and dies. On a success, gain poison resistance for 1d4 days.

21-30

Minor Explosion. Roll a DC 12 Dexterity saving throw. On failure, you suffer 2d10+your level fire damage, and your laboratory needs 50 gp of repairs. On a success, your laboratory needs 100 gp of repairs, but you gain fire resistance for 1d8 days.

31-40

Strange Fumes. All creatures within 120 ft roll DC 13 Wisdom saving throws. On a failure, they suffer psychedelic nightmares for a week and have to pass new Wisdom saving throws to complete a long rest. On a success, they gain advantage on saving throws against the frightened condition and confusion for 1 week.

41-50

Mutagenic Vapors. Roll a DC 13 Constitution saving throw. On a failure, you gain vulnerability to fire, cold, or lightning damage (your choice) for 1d8 days. On a success, gain resistance to one damage type of your choice for 1d8 days.

51-60

Destructive Explosion. Roll a DC 14 Dexterity saving throw. On a failure, one piece of your gear worth at least 25 gp is destroyed. On a success, when you deal fire damage to a creature for the next month, you can also push that creature 10 feet away from the point of impact.

61-70

Acid Burst. Roll a DC 14 Dexterity saving throw. On a failure, your laboratory notes are damaged, and you must spend 1d20 days restoring them before you can use this downtime activity again. On a success, when you deal acid damage for the next week, you can reroll all 1s and 2s, keeping the new result.

71-80

Thunderstone. Roll a DC 14 Constitution saving throw. On a failure, all glass within 500 feet shatters; creatures within 5 feet of large amounts of glass roll DC 12 Dex saves, suffering 2d6 piercing damage on a failure. If you succeed your saving throw, whenever you deal fire or lightning damage for the next month, you deal an additional 1d8 thunder damage.

81-90

Wild Insight. Roll a DC 15 Intelligence saving throw. On a failure, you gain vulnerability to psychic damage for 1d8 days. On a success, you can cast hideous laughter without expending a spell slot or using any components. Once you do, you may not do so again until you complete a short or long rest. This benefit lasts for one month.

91-100

Magical Interference. Roll a DC 20 Intelligence (Arcana) check. On a failure, you suffer disadvantage on saving throws against spells for 1d6 days. On a success, gain one available spell slot for the highest level of spells you can cast for one week.

101-110

Coughing Fit. Roll a DC 16 Constitution saving throw. On a failure, you suffer disadvantage on saving throws to maintain concentration for 1d8 days. On a success, you can cast gust of wind without expending a spell slot or any components. Once you do, you must complete a short or long rest before you may do so again. This benefit lasts for one month.

111-120

Refiner's Fire. You can destroy 10 lb. of silver (500 sp) to grant one weapon, arcane focus, shield, or suit of armor a magical +1 bonus to attack and damage rolls for 1 month. You must acquire the silver and the item to be enhanced within 1 day of completing this experimentation. Only one item may be enhanced in this way per die roll.

121+

Chrysopoeia. You transmute base materials into gold, creating 4d20 x 20 gp.

Design Notes

The concepts of many of these results come from previous work I've done on alchemical crafting systems for tabletop games. That work proved to be interesting, but a bit too convoluted for easy use at the table; it's possible that it would have gotten better once the player could easily resolve it without DM attention, but we dropped it well before that point.

In these charts, I wanted to make sure that almost all of the outcomes are a roughly even balance of possibly good and possibly bad, with the more positive outcomes toward the higher roll results, so that you do get a little better with level. Even low-level characters can greatly benefit from alchemical experimentation, with some luck.

Note that this isn't a research system in any sense - instead, it is a variation of Carousing that allows much stranger outcomes. If you want a research system, I worked up one of those, too.