I was wondering if taking keen mind feat can help me copy spells from a spell scroll? If I fail the arcana check I can't copy and the scroll is destroyed, but with keen mind I should be able to remember what the spell scroll looked like. Can I keep tying to copy the spell, or do I need the scroll?

DM's call. There is no real RAW of it.

However, I don't have spell scrolls require Arcana rolls to copy from it and I don't require the scroll to be used up if you copy from it. This is because these things make no sense at all to me, given that you can, by RAW, copy a spell from another spellbook with no checks or risks. A spell scroll is just paper enchanted to cast the spell written upon it but nothing says you can't read from it without casting. So, you should be able to copy from it that way. 

And yes, I'd totally allow you to copy the spell if memorised with keen mind or recreated using Minor Illusion or something. It's not like it's some cheat or something - I'm the DM, if I don't want you to find the spell, you simply won't find it. 

I mean the Fighter doesn't have to make checks if I give them a new sword, or have him risk losing the sword forever. It's his reward, after all. Wouldn't be much of a reward, now would it? The spell scroll is the Wizard's reward: a new spell for their spellbook and one free cast without prepping. Seems decent enough. Especially given the fighter doesn't have to spend gold and time to use his sword, unlike the Wizard. I see no reason to nerf the wizard with such illogical shitfests. 

In my games if you find a spell scroll - it's because I've chosen to give you that spell. Scribe away, risk free, ma spellchuckin' dude.

I don't know what arcana check you are referring to: 

Copying a Spell into the Book. When you find a wizard spell of 1st level or higher, you can add it to your spellbook if it is of a spell level you can prepare and if you can spare the time to decipher and copy it.

Copying that spell into your spellbook involves reproducing the basic form of the spell, then deciphering the unique system of notation used by the wizard who wrote it. You must practice the spell until you understand the sounds or gestures required, then transcribe it into your spellbook using your own notation.

For each level of the spell, the process takes 2 hours and costs 50 gp. The cost represents material components you expend as you experiment with the spell to master it, as well as the fine inks you need to record it. Once you have spent this time and money, you can prepare the spell just like your other spells.

I don't see anything mentioning an arcana check.

But if there is an arcana check you want to bypass with that logic what is the point of the Spellbook (you can use the same logic to just remember all the spells)? Especially using the minor illusion cheese. Why even get the spell scroll? Just check it in the store, create an illusion and free spells.

If I were the DM, I would not allow it. It can open up some unforseen consequences. If I wanted to make this easier I'd remove the arcana check.

Quote from xinagent >>

I don't know what arcana check you are referring to: 

Copying a Spell into the Book. When you find a wizard spell of 1st level or higher, you can add it to your spellbook if it is of a spell level you can prepare and if you can spare the time to decipher and copy it.

Copying that spell into your spellbook involves reproducing the basic form of the spell, then deciphering the unique system of notation used by the wizard who wrote it. You must practice the spell until you understand the sounds or gestures required, then transcribe it into your spellbook using your own notation.

For each level of the spell, the process takes 2 hours and costs 50 gp. The cost represents material components you expend as you experiment with the spell to master it, as well as the fine inks you need to record it. Once you have spent this time and money, you can prepare the spell just like your other spells.

 

I don't see anything mentioning an arcana check.

But if there is an arcana check you want to bypass with that logic what is the point of the Spellbook (you can use the same logic to just remember all the spells)? Especially using the minor illusion cheese. Why even get the spell scroll? Just check it in the store, create an illusion and free spells.

If I were the DM, I would not allow it. It can open up some unforseen consequences. If I wanted to make this easier I'd remove the arcana check.

The rule you're missing is on spell scrolls.

Quote from xinagent >>

I don't know what arcana check you are referring to: 

Copying a Spell into the Book. When you find a wizard spell of 1st level or higher, you can add it to your spellbook if it is of a spell level you can prepare and if you can spare the time to decipher and copy it.

Copying that spell into your spellbook involves reproducing the basic form of the spell, then deciphering the unique system of notation used by the wizard who wrote it. You must practice the spell until you understand the sounds or gestures required, then transcribe it into your spellbook using your own notation.

For each level of the spell, the process takes 2 hours and costs 50 gp. The cost represents material components you expend as you experiment with the spell to master it, as well as the fine inks you need to record it. Once you have spent this time and money, you can prepare the spell just like your other spells.

 

I don't see anything mentioning an arcana check.

But if there is an arcana check you want to bypass with that logic what is the point of the Spellbook (you can use the same logic to just remember all the spells)? Especially using the minor illusion cheese. Why even get the spell scroll? Just check it in the store, create an illusion and free spells.

If I were the DM, I would not allow it. It can open up some unforseen consequences. If I wanted to make this easier I'd remove the arcana check.

 
As quindraco has stated it is on the spell scroll magic item where the rule about arcana check is stated.

And as for the "why even get the spell scroll" - because no shop is going to let you read and memorise/copy it before purchase. You could buy, open in store to check it's the real scroll, and if not the right one return for refund before leaving, if is the right spell, leave with it. 

And for the spellbook - because preparing a spell into the mind for casting is not the same thing as memorisation and so you can argue that the keen mind feat is not sufficient to compensate for the mental exercises needed, so you must rely on the book to properly prepare it. Using minor illusion you could replicate page by page and memorise, but I'd feel that some higher spells take more than one page and using minor illusion means you have to recast every six seconds to "turn a page" that normally takes less than 1 - so you could memorise with minor illusion + keen mind, but it'll take 6 times longer, at least. This isn't "cheese", especially given it's perfectly RAW for a conjuration wizard to use their 2nd level feature to summon a copy of the spellbook and memorise from it. There's literally no advantage to this other than it makes it easier to secure the spellbook - but they can secure it easily enough anyway and I can always just use antimagic or curse the player or whatever, if I need to take away their spellbook/memorisation or whatever. Although, I'm very unlikely to do that.

As a DM I know what features you have and what you can do with them. So if I know you can memorise with a glance for perfect recall - and there's a spell I'll allow but not without cost - then you can only purchase before reading, to prevent bypassing the cost. A simple and easy thing, given that there are some stores with similar rules here in real life. 

I can also just say the shop has a way to protect their scrolls from being memorised and once purchased they release it, or something. I can invent any sort of magic I want, I'm the DM. 

I'd rather say "yes" and come up with a counter if I end up really needing to, than say "no, never". It's more fun that way.

Quote from quindraco >>

Quote from xinagent >>

blalba 

The rule you're missing is on spell scrolls.

Thanks, bit odd not having it on the wizard page and I was too lazy to scroll that far on the scroll page. 

Quote from Cyb3rM1nd >>

Quote from xinagent >>

blabla

 

 
As quindraco has stated it is on the spell scroll magic item where the rule about arcana check is stated.

And as for the "why even get the spell scroll" - because no shop is going to let you read and memorise/copy it before purchase. You could buy, open in store to check it's the real scroll, and if not the right one return for refund before leaving, if is the right spell, leave with it. 

And for the spellbook - because preparing a spell into the mind for casting is not the same thing as memorisation and so you can argue that the keen mind feat is not sufficient to compensate for the mental exercises needed, so you must rely on the book to properly prepare it. Using minor illusion you could replicate page by page and memorise, but I'd feel that some higher spells take more than one page and using minor illusion means you have to recast every six seconds to "turn a page" that normally takes less than 1 - so you could memorise with minor illusion + keen mind, but it'll take 6 times longer, at least. This isn't "cheese", especially given it's perfectly RAW for a conjuration wizard to use their 2nd level feature to summon a copy of the spellbook and memorise from it. There's literally no advantage to this other than it makes it easier to secure the spellbook - but they can secure it easily enough anyway and I can always just use antimagic or curse the player or whatever, if I need to take away their spellbook/memorisation or whatever. Although, I'm very unlikely to do that.

As a DM I know what features you have and what you can do with them. So if I know you can memorise with a glance for perfect recall - and there's a spell I'll allow but not without cost - then you can only purchase before reading, to prevent bypassing the cost. A simple and easy thing, given that there are some stores with similar rules here in real life. 

I can also just say the shop has a way to protect their scrolls from being memorised and once purchased they release it, or something. I can invent any sort of magic I want, I'm the DM. 

I'd rather say "yes" and come up with a counter if I end up really needing to, than say "no, never". It's more fun that way.

I had a DM who said too many yeses and then came up with convoluted counters to the yeses that made them basically nos. That was more annoying than having the nos in the first place. 

Anyway we can disagree on this. I still think that removing the need of the check would have a similar result (having a 100% chance to copy the spell) without any of the baggage. You also get the added benefit you don't have to pay the price and time again if you fail, I'd argue it is a bigger buff for this purpose. That is if you want your wizard to have all the spells you give them as scrolls.

If OP needs more "source" I found some other threads that discuss this (or similar) topics:
Reddit

rpg.stackexchange

dndbeyond

I don't think there is a conclusion on this. I think both parties have valid points. You will end up with whatever your DM says anyway. :)