So my first take on this class.
At its core, this class is a "mundane combat class" + "magical buff class". Lets look at both.
Combat Class
Until you get to the d6 with reroll, there is no way I would ever cast spells in combat, and even then its probably only 1st level spells.
So I'm using cantrips, weapons, tactical chemistry, or my archetype abilities like my grenades as my combat options. That's fine, we can work with that....but I feel like the spell list doesn't understand this. I can't ever see this class casting fireball, at the best chance possible its a 1/4 complete flub, and its much much higher than that most of the time. And wall of fire at 4th....forget about it. Eldritch cube at 5th...no way jose
Now...if all the fizzle die did was make it so I lost the action, it would still be an unacceptable risk most of the time, but for those gambler people out there I could maaaybe see it. But its even worse, I lose the ability to cast the spell entirely. Now if the artificer had 10 spells at their command, ok I could work with that. But no...its 2 or 3 spells for the majority of a standard adventurer's career. There is no way I am risking losing 50% or 33% of my entire spell repertoire for the day to try some high level combat spell.
So at the end the day, I have a mundane combat class that doesn't get extra attack or sneak attack or rage or smite. So a lot of the "magical buff side" is going to be spent JUST to get me to basic parity with other classes, let alone getting ways to shine.
Combat Summary: In summary, any combat spell higher than maybe 2nd should be removed from teh list, or the fizzle die mechanic needs to be tweaked. Right now any spell that is expected to be in cast in combat and higher than 1st or 2nd level is a complete trap. So either remove teh spells and just focus on the buff/non-combat aspect of the class....or you need some more ways to control the fizzle die (such as using an infusion to repair a spell invention or something like that).
Magical Buff Class
On this side I think the class is a lot cooler looking. The flavor of "quasi-infinite" abilities is cool. I can make magic items, I can buff my party with neat effects, I might be able to provide a lot of out of combat healing. I like the concept here.
My biggest issue is the number of prepared spells. It just feels so low compared to other classes.
At the end of the day while the flavor of the class is neat....but what is this class really bringing to the table spellcaster wise? I'm never upcasting spells, too much risk. I don't have true at-will casing like warlock invocations. At some point I can cast lots of low level spells (probably) but never get to cast higher level spells. I still suffer concentration restrictions, which also diminishes the "mass cheap spell" potential of this class.
I will now repeat myself from the previous section: "So at the end the day, I have a mundane combat class that doesn't get extra attack or sneak attack or rage or smite. So a lot of the "magical buff side" is going to be spent JUST to get me to basic parity with other classes, let alone getting ways to shine."
Considering the effort I have to go through to get back to that parity, I don't think there is enough left to let the class "shine" in any unique way.
Magical Buff Summary: I think this is the strength of the class right now, but it feels like its missing something to really make it unique compared to other spellcasters. It has a unique mechanic, but ultimately what does this class do "better" spellcasting wise than other classes.
Ideas: These would be my off the cuff thoughts, worthy to try while its in beta.
- Have the invention cast the spell. This opens up a whole new world. Now the artificer could have 2 or more concentration spells going at once (though he still can't spam the same concentration spell multiple times because the invention is concentrating). Now you could do a bonus action and a regular action spell. Suddenly the artificer is capable of combos that normal spellcasters are not, but still restrained by the extra restrictions they have. That is COOL.... now we have something to sink our teeth into.
- Allow the same spell to be prepared multiple times. If my artificer wants to be a "wall guy" today, and just belt out walls of stone at the cost of that being his only spell today, why not let him. Aka let him make an invention and a few "backups", this opens up a lot more potential spell list builds.
- More ways to control the fizzle die. Even ignoring combat, it really feels like I'm gambling way too much with spellcasting right now. Maybe allow infusions to be spent to repair the invention. Or maybe allow every spell (of X level depending on my artificer level) to be ritually cast (that would be a unique power of the artificier). One way or the other, I do feel there needs to be more control here. Nothing would be more "feels bad man" than an artificer starts their day, roll two flubs on fizzle, and now just lost all of their spellcasting for the entire day. And based on the current flub rates....its going to happen a good amount, and I think that will just be too frustrating for people.