A player in my game wants to add an artificer character. I have Tasha's, so it is the version of the class we will be using, although I am reading it for the first time today and have not read the versions in UA or Eberron.
In the level progression block on page 10, there is no column for total number of spells known, like a half-caster.
The rules for preparing artificer spells are on page 11. They say, in part,
You prepare the list of artificer spells that are available for you to cast, choosing from the artificer spell list.
This seems to imply that an artificer can prepare any spell from the class list, although it would have been more clear had they said "choosing from the entire artificer spell list." This makes it seem like artificers are meant to be like clerics and druids, in which they are assumed to know all spells. Or more properly, when they attain a class level, they know all the spells of all the spell levels that their class level can cast.
However, on page 12 it says:
Here's the list of spells you consult when you learn an artificer spell.
And there is no mechanism presented for learning spells, such as a wizard has for adding spells to a spellbook. As far as I can tell, there are no rules for under what circumstances you can learn an artificer spell.
So, what does "Here's the list of spells you consult when you learn an artificer spell" mean, if an artificer would never be learning an artificer spell, but rather, a whole group of them at once?
And if there is a mechanism for learning individual spells, what is it, and is there a hard limit to the number of spells known?
Best Answer
Spells Available
Your instinct is correct: the artificer is more like a cleric than a wizard when it comes to spells known. They prepare spells daily from the complete list available (which includes subclass spells).
The mechanism for changing the spells prepared is at the bottom of page 11 of TCOE:
The flavor of this is that the artificer is modifying their chosen objects (e.g. substances, tools, or devices) to cast the new spells. For example, maybe a mechanical spider used to spit venom for a poison attack, but now it will weave webs to close wounds for a healing spell.
Ritual Casting
Note that the similarity between artificer and cleric casting extends to ritual spells. Both class descriptions say:
The wizard, though, is different:
"Learning" an Artificer Spell
Chapter 11 of the PHB introduced the 12 original classes' spell lists by saying:
When TCOE expanded other classes' spell lists, they said something like this:
Unfortunately, TCOE's authors didn't follow this bare bones approach when introducing the artificer's spell list. Instead, they used the more friendly wording you quoted, which introduced the word "learn." As you've highlighted, this word is loaded based on its use with wizards' spellcasting.
Clearly, however, the artificer doesn't gain spells the same way a wizard does. For wizards:
Compare this with the sorcerer, whose player chooses a subset of spells at each level:
Importantly, with the sorcerer, there's no mention of preparing spells.
The Bottom Line: For clarity, TCOE's authors should have said "when you prepare an artificer spell" instead of "when you learn an artificer spell."
Minor Caveat: Cantrips
Cantrips are the one place where "learning" spells has relevance -- though, again, just like the cleric:
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