Pretty much replacing magic items with player-created consumables. I like this because it gives players something to do during downtime, and introduced an element of time management–players are only going to be able to squeeze in one or two created items a day.

All alchemical processes require ester, a stable form of raw element created by alchemists. Ester types are:

Acid

Cold
Fire
Force
Lightning
Necrotic
Poison
Psychic
Radiant
Thunder
Alchemists must collect ester from the corpses of elementally aligned creatures. A creature is elementally aligned to the damage type it deals (excluding slashing, bludgeoning, and piercing damage). If a creature does not deal typed damage, it does not have any ester in its body. To harvest ester, a character must succeed a DC 15 Intelligence (Arcana) check and have one hour of uninterrupted access to the remains of an elemental creature. Tiny, Small, and Medium creatures contain 1 lesser ester; Large creatures contain greater ester, and Huge and larger creatures contain 1 grand ester. Failing a check to harvest ester destroys all the ester in the creature’s body and prevents further attempts. 

Once collected, ester can be used to create alchemical devices. Creating an device requires 8 hours of work and an Intelligence (Alchemy kit) check. A failed check means all ester used has been destroyed. In order to attempt to create a device, a character must know about it. They generally discover new devices by finding ancient schematics. Schematics depict a particular kind of device, so aspiring alchemists must learn to make lesser seals and greater seals separately, for example.

Devices
Seals
Alchemical seals are attuned with the same element as the ester used to create them. Weapons affixed with an alchemical seal deal damage of the same type as that seal. All last 1 minute before crumbling.

  • Lesser Seal: 1 lesser ester and DC 15 to make. Weapon deals typed damage and gains +1 to damage rolls.
  • Greater Seal: 1 greater ester and DC 20 to make. Weapon deals typed damage and gains +2 to damage rolls.
  • Grand Seal: 1 grand ester and DC 25 to make. Weapons deals typed damage and gains +3 to damage rolls.

Munitions
Spheres containing a volatile form of ester; detonate when thrown or otherwise broken, dealing damage of the same type as the ester used to make them. They also produce an effect pertaining to their element (Radiant munitions produce a flash of light, Acid munitions corrode metal and stone, Necrotic munitions wilt plants, and so on). Thrown munitions have a range of 20/60.

  • Lesser Munition: 1 lesser ester and DC 15 to make. The target must make a Dexterity save or take 2d6 typed damage. They take half damage on a success.
  • Greater Munition: 1 greater ester and DC 20 to make. All creatures in a 10 foot sphere around the point of impact must make a Dexterity save or take 5d6 typed damage. They take half damage on a success.
  • Grand Munition: 1 grand ester and DC 25 to make. All creatures in a 15 foot sphere around the point of impact must make a Dexterity save or take 7d6 typed damage. They take half damage on a success.

Homunculi
Elemental spirits sealed inside a glass vessel. Creating a homunculus requires 1 lesser ester of each type and DC 20 to make.

  • Homunculi cannot leave their bottles or perform any sort of physical activity; the only thing they can do is speak. They have 1 HP, 0 AC, automatically fail all Strength, Constitution, and Dexterity saving throws, and automatically succeed all Intelligence, Charisma, and Wisdom saving throws. They are loyal to the last creature to hold their bottle. 
  • When making checks to answer questions about alchemy, homunculi add twice the alchemist’s proficiency bonus at the time of their creation to the roll. 
  • When creating a homunculus, the player does not know whether or not they succeed the check; if it fails, they still create the homunculus, but it provides subtly erroneous information.

Alchemical Cannon

Martial ranged weapon with the Ammunition, heavy, loading, and two-handed properties. Range is 150/600. Requires 1 greater ester of each type and DC 25 to make. Uses esters as ammunition; the damage it deals depends on their quality:
  • Least ester: 2d4+Intelligence* typed damage
  • Greater ester: 2d6+Intelligence* typed damage
  • Grand ester: 2d8+Intelligence* typed damage

*Intelligence of the alchemist who created the cannon at the moment they created it. The wielder does not add their Dexterity modifier to cannon damage like other ranged weapons. 


Elixirs
The ultimate alchemical achievement. Requires 1 grand ester of each type and DC 30 to make. Anyone who drinks an Elixir does not age naturally or magically.