Alchemists are a spellcaster class that relies on TEC-based attacks. TEC attacks work differently from normal, STR-based attacks--they use the TEC stat, as you might be able to infer, they do not take weapon ATK into account at all, and when a player is using a TEC-based attack against an enemy, the damage calculation factors both the target's TEC and VIT when determining defense. Generally speaking, Alchemists are very, very good damage dealers, mostly because most enemies in the game (including nearly every boss) has an elemental weakness, meaning that not only do they deal increased damage compared to a physical damage of roughly equal power, they also have a buff that provides a 50% damage increase when hitting a weakness. The downside to all this is that Alchemists have far higher TP costs for their skills relative to other classes, and are extremely fragile.


Stats

(Full stat table)

Alchemists have very bad HP, STR, and VIT. They obviously don't give two shits about STR, but their low HP and VIT means they're very, very fragile, even in the back row. Their AGI's decent, but they're always going to be pretty slow due to staves having negative speed modifiers. Their TP and TEC are the highest of any class, and their LUC is the second-highest of any class. They actually make for fairly decent disable inflicters due to their TEC/LUC spread.

Common Passives: TP Up
Gathering Skill: Chop


Formula Mastery


Required to learn Formula skills. Increases damage dealt with Formula skills.

Fire Formula / Ice Formula / Volt Formula


Deals ranged TEC-based fire/ice/volt damage to one enemy. Has an 80% speed modifier and a base accuracy of 99% at all levels.
I collectively refer to these as the "tier 1 Formulas."

The most basic Formula skills. They deal damage, they certainly do. You'll want all of these maxed out by the endgame, and at least level 5 by the midgame. The tier 2 Formulas do deal more damage than these, yes, but not by much--Flame Formula deals 50% more damage at level 10, Freeze Formula deals 35% more damage, and Spark Formula deals a measly 10% more damage at level 10. All of these cost 18 more TP at level 10 than the tier 1 Formulas.
Alchemist's "hit thing" skills of choice for a significant majority of the game. You'll want to have these.

Inferno Formula / Cocytus Formula / Thor Formula


Deals ranged TEC-based fire/ice/volt damage to all enemies. Has a 60% speed modifier and a base accuracy of 99% at all levels.
I collectively refer to these as the "tier 3 Formulas."

The big problem with the tier 3 Formulas, to me, is that it'd be preferable to have all of them available for the sake of coverage, but each of them requires five points in their respective tier 1 skill to unlock. Given that, I'd honestly advocate for picking either Inferno Formula or Thor Formula by the endgame and postgame--not enough things are weak enough to ice for Cocytus Formula to be attractive.
These skills are outright better than tier 2 in every possible way, so once you can tolerate level 5+ tier 1 TP costs I'd suggest moving to these ASAP.

Flame Formula / Freeze Formula / Spark Formula


Deals ranged TEC-based fire damage to one enemy, with splash damage. Has a 70% speed modifier and a base accuracy of 99% at all levels.


Deals ranged TEC-based ice damage that pierces enemy rows. Has a 70% speed modifier and a base accuracy of 99% at all levels.


Deals ranged TEC-based volt damage to one row of enemies. Has a 70% speed modifier and a base accuracy of 99%.
I collectively refer to these as the "tier 2 Formulas."

The tier 2 Formulas occupy an awkward space between the tier 1 Formulas' TP efficiency (relative to the tier 2s, anyway) and the tier 3 Formulas' multi-target coverage. Like I mentioned above, they don't deal enough damage compared to the tier 1 Formulas at equivalent levels for the TP increase.
These have a place in the early-midgame as an area of effect option that doesn't require you to spike your single target attacks' TP cost, but ultimately their efficacy is fairly short-lived as tier 3 is more effective for the exact same TP costs..

Dilution


Reduces all enemies' elemental defense for a set amount of turns. Has no speed modifier at all levels.
Dilution's an okay defense debuff, honestly, since you're going to ideally want to be hitting fire/ice/volt weaknesses most of the time, especially in boss fights. However, Alchemists have a certain buff that they already want to take a turn to set up...
This is one of the strongest element defense debuffs from a player source, but there aren't many elemental attackers in EOU Classic besides Alchemist themselves and chaser parties. It's certainly a very Story party-oriented skill.

Analysis


Increases the user's attack when hitting an enemy's weakness for a set amount of turns. Has a 90% speed modifier at all levels.
Yes, Analysis ate a serious nerf in EOU compared to its EO2, EO3 (Singularity), and EO4 (Runic Guidance) versions. It's now a buff you have to have your Alchemist use a turn to set up.

Now, Analysis is still, like, insanely good, mind you. An extra 50% damage on top of hitting a weakness means your Alchemist gets 87.5% more damage than normal when hitting a 125% vulnerability, and 125% more damage when hitting a 150% weakness. That's not even getting into the level 15 version, too.
This is pretty much a must-have skill for Alchemist. For any fight where a weakness is involved (quite a few), Analysis is an extremely powerful personal buff for damage output.

Pain Formula


Requires that the user be in the front row to use. Deals melee TEC-based bash damage to one enemy.
...Buh? What? Melee-only TEC-based bash damage? Why would you ever use this? It deals far less damage than even the tier 1 Formulas for an almost equivalent level 10 TP cost, and no bosses are weak to bash! Certain normal enemies and a handful of FOEs are, but... What???
There is an edge-case purpose for this skill. Notably, if no elemental weaknesses are present this combined with Firelight are the highest damage per turn for an Alchemist. The combination is quite TP efficient, and can possibly edge out Inferno Formula against a fire weak enemy for being almost twice as TP efficient for roughly 8% less damage. That front-row requirement is pretty dangerous, though.

Firelight


At the end of the turn, deals ranged TEC-based fire damage to the target of Pain Formula, or to any enemies that activated Light Formula or Light Tincture.
See the above comment. There's the proc on Light skills as well, but those are less of a consideration.

Light Formula


Nullifies physical damage to the user for one turn. Each time Light Formula activates, the chance if it activating again on that turn is reduced.

Light Tincture


Nullifies elemental damage to the user for one turn. Each time Light Tincture activates, the chance if it activating again on that turn is reduced.
Both of these skills are odd. The primary usage I could imagine for these would probably be on a Provoked Protector, but frankly that's enough hoops to jump through that I'd consider it a gimmick at that point.

Return Formula


Can only be used in the Labyrinth. Attempts to exit the Labyrinth and return the party to town.
...To be honest, there's far worse things you could spend five (effectively six) skill points on than a permanent replacement for an Ariadne Thread.
This is a pretty superficial convenience and more SP than I'd care for just to avoid making sure I didn't forget to do something.

Flee


The user consumes a percentage of their current HP to attempt to escape from the current battle. If successful, Flee will place the party at the location they entered the floor from.
Double nah.
Honestly, it'd be nice to have this at Lv.10 on a Grimoire Stone because EOU's escape rates are the pits and some encounters can really use an emergency escape. The only problem is actually, yknow, putting in the SP and getting a Stone with it.

Alchemy


When an item is thrown away, the party receives a percentage of its sell price as money.
lol what the fuck
Oh no, I brought 50 Medicas to the dungeon and ran out of space! Better blow them up!

Scavenge


Increases monster drop rates.
Ugh. Barely does anything at all, especially when up against atrocious drop rates like 15%.
Begrudgingly, this has some significant uses. EOU absolutely screwed me up with its drop rates, and there are some quests later that involve a large amount of low rate drops. Anything to make that less bad is welcome.

Sight Formula


Reveals FOE positions on the map in an area around the party.
lol what the fuck

it's in bold this time
This is probably one of the few skills in the game that I can confidently call utterly worthless. EOU doesn't have the baffling map limitations that EO1 and EO2 had for FOE detection, so the already limited value the skill had there is gone entirely.

Focus


Restores the user's TP at the end of each turn if their HP is full.
Ewwww.
This is even less of an argument for Alchemist, since they deal with much larger TP costs than Medic.