So my latest thing of homebrew that I've been working on is a reworking of the old Wizard Lore mastery subclass. I know I have my work cut out for me trying to rebalance that subclass due to it being over powered, but I feel like I'm on the right path to something even though I know I have ways to go. I do have ideas on what I can do from here to help balance it better, but I'm wanting an outside opinion before I proceed.

Arcane Scholar
Beginning when you select this school at 2nd level, you learn two languages of your choice, and choose two of the following skills to gain proficiency in; Arcana, History, Nature, or Religion. Your proficiency bonus is doubled for any ability check you make that uses either of the chosen proficiencies.

Researcher's Essentials
At 2nd level, you have prepared yourself with the means to safely unlock different kinds of secrets during your adventures. Add comprehend languages, and identify to your spellbook if they are not already there. You also have advantage on saving throws against being charmed, frightened, and other effects that cause madness.

Arcanist's Focus
At 6th level, you have discovered the methods of creating and empowering arcane focuses with your own magic like the wizards of old. You can spend 8 hours and 50gp of supplies to create an Arcanist's Focus, or spend 1 hour and 25gp worth of supplies to imbue an arcane focus to become an Arcanist's Focus. When you create the Arcanist's Focus you can choose one of the following effects that you can use as a bonus action when you cast a spell.

• You can cast the spell without its material component(s) if it is no higher than a 5th level spell, requires a gold cost no more than 100gp and does not consume the component(s) on use.
• When you cast a spell that deals, acids, cold, fire, force, lightning, poison or thunder damage, you can substitute that damage for any other damage type from that list.
• When you cast a spell with a spell slot that requires a Strength, Dexterity, or Constitution Saving Throw, you can change the spell's first saving throw to Strength, Dexterity, or Constitution.
• When you cast a spell with a spell slot that requires a Intelligence, Wisdom, or Charisma Saving Throw, you can change the spell's first saving throw to Intelligence, Wisdom, or Charisma.

You can choose an additional effect to add to your Arcanist's Focus at 10th level, 14th level, and 18th level. Only you can benefit from the feature's of the Arcanist's Focus, but other caster may use the Arcanist's focus as an arcane focus. If you create a new Arcanist's focus while one already exists, the previous one is no longer functions as an Arcanist's focus. If the focus was created, it is destroyed or if the Arcanist's focus was preciously an arcane focus, then it reverts to an arcane focus instead.

Scholar's Preparation
Beginning at 10th level, you are always prepared to look up the spell that you need, even if you didn't think that you would. As a bonus action, you can replace one spell you have prepared with another spell from your spellbook. You can’t use this ability again until you finish a short or long rest.

Arcanist's Secret
Starting at 14th level, you have unlocked the secret of how to use all of the arcane energy stored in an Arcanist's Focus in a single cast. When you choose to do so, choose one of the following effects for the next spell you cast on this turn:

• The spell is cast as if it was cast at 9th level.
• The spell is cast as an action.
• You can cast the spell without the required material components.

After you use an Arcanist's Focus in this way, it is destroyed, unless the Arcanist's Focus was previously an arcane focus, then it is no longer an Arcanist's Focus and cannot be used as an arcane focus for 1 hour. You cannot create another Arcane Focus (both methods) until you finish long rest.

Did you post something like this a week ago? I'm having deja vu.  Edit: Never mind; someone else posted a "Librarian" subclass that also had spell swapping.

Is Scholar's Preparation too OP to have at 2nd level?

I think maybe the Arcanist's Focus should have more options, so that you don't get all 4 at the end? Also, does this mean at 10th level I can apply two options to a spell, or I can apply one or the other option?

I'd also say for simplicity's sake, the focus is destroyed either way for Arcanist's Secret. Arcane foci are common enough to have a spare, right?

Is Scholar's Preparation too OP to have at 2nd level?

It probably wouldn't be too strong for that, but my reasoning for having it at 10 instead at 2 is because the level 6 feature is strong. My thought was to try out having the main feature at 6 instead of 2. Another option for that one I was thinking of possibly doing a "once per day during a short rest you can replace a number of spells equal to you Intelligence modifier from you spellbooks that you have prepared with the same number of spells from your spellbook. In addition, you take half the time to prepare spells from your spellbook."

I think maybe the Arcanist's Focus should have more options, so that you don't get all 4 at the end? Also, does this mean at 10th level I can apply two options to a spell, or I can apply one or the other option?

At first I was going to, but after some more work, I started to realize that I was basically making a scholar variant of my school of infusion subclass (which is just a wizard with meta magic). I'd like to keep it no more than 4 options if I can, and you only use one effect at a time. As you level you are able to choose a additional/different effects if you so please, such as like meta magic. In my previous version I had it so that the caster just had all the options, which after some thought was just too much versatility in my opinion.

I'd also say for simplicity's sake, the focus is destroyed either way for Arcanist's Secret. Arcane foci are common enough to have a spare, right?

True enough, I'll just switch it to that, it is just easier and makes sense. Besides they already get enough of a benefit of using the focus by having a massive gold and time reduction.

Did you post something like this a week ago? I'm having deja vu.  Edit: Never mind; someone else posted a "Librarian" subclass that also had spell swapping.

Yeah I think I was helping that person out a bit then got interested in doing my version again. The last thing i posted about was my beserker barbarian revamp, which no one commented about, but I have finished it (though they're still might be typos and such).