A recent thread on an RPG forum sparked a debate about the legitimacy of the rogue subclass, rogue-alchemist. The author argues that because the subclass is not officially in D&D 5e, it does not have any mechanical presence and is therefore not valid. However, this argument ignores how new official classes are made: by taking two existing classes and altering one or more of their mechanics. This includes both existing official classes as well as new subclasses which are not yet part of the game’s release material. Rogue-alchemist is neither an example of either type — it is a completely brand new class, so there should be no objection to using its mechanics in your campaigns.
Rogue Subclasses 5e
The logic behind that proposed class is based on speculation as to how rogue-alchemist would work in terms of mechanics: the subclass gains a unique feature that is functionally identical to existing rogue abilities, but which also confers upon the character exclusive knowledge of alchemical ingredients. It strikes me that this argument is based on faulty assumptions about the way rogue subclasses 5e works.
I cannot demonstrate this with facts, only with reasoning and analogy: suppose you were going to write the rules for an absolute beginner’s soccer game. Rather than giving players input options such as pass, shoot or kick, you decided to give them a list of five pre-chosen actions instead; each player takes one action from the list every turn.
Rogue Subclasses 5e: rogue-sorcerer
This logic is applied to the 5e rogue: a player does not choose from a list of actions as in soccer but rather chooses from five pre-defined character options. Those choices are the core rogue abilities: evasion, sneak attack, and expertise (the three most popular), trap finding, and stealth (the two least). There are two flaws with this line of reasoning. First, D&D 5e does not work like soccer — every character is unique, with a unique build of abilities, ability scores, and powers.
Second, the list of options for soccer is not a complete list — just like the rogue class, it is an incomplete list of possibilities. Now imagine we rebuild soccer from scratch. Rather than five pre-chosen actions, we give players a page of rules and ask them to choose their own actions from those listed. We have not changed the system that much — “soccer with custom rules” is still D&D 5e — but it does change how action rolls are made.
You cannot claim that rogue-alchemist is not valid because the class is not officially in the core rulebook. So what if you want to use the mechanics of rogue-alchemist, but you are concerned about potential confusion with existing official classes? The only such case I can think of would be a rogue sorcerer. One method to consider this is to ask whether your campaign world uses magic (and, possibly, a different alignment system). If so, you wouldn’t prevent players in your campaign from using this class by using it in an unauthorized manner.