Learning more spells and additional features is always more fun! This campaign will allow PCs to gain new abilities outside of their normal level-ups. Traditionally in 5e, only wizards can learn spells by copying a spell into their book. But what about all the other classes like Paladins, Bards, Sorcerers and such?

Story Spells and Level Up Spells

During this campaign there's a distinction between "Story Spells and "Level-up Spells"

A "Story Spell" is a unique spell that a player can learned which is outside of their typical class restriction rules. These can be official or custom spells granted by the DM.

A "Level-Up" Spell is a spell that a player gains access to upon level-up. Typically the DM and player have already discussed which spell(s) this will be. These spells could be learned through the use of a spell scroll, ancient scripture or in some other way weaved into the narrative, but a player can gain access to such a spell a bit earlier than normal.

Rules for learning a "Story Spell"

Learning a Story Spell could be an entire quest!

Any caster can learn a spell from an NPC who has mastered a particular spell. This typically requires an Intelligence (Arcana) DC check determined by the DM + its spell-level. If you pass that check, you learn that spell. Sometimes there may be a gold cost, item cost or time cost which will be announced before the check is made. On a failure these costs are still used.

On a failure, not everything is lost. Typically trying again some time later is possible, and whatever you learned during the experience hasn't gone to waste. Sometimes the related NPC will grant a spell scroll. A non-caster can also learn a spell but it usually requires some magical object to channel the spell through. The DM will typically give every PC the opportunity to learn one story spell per level.

Due to wizards being able to scribe spells, make sure to communicate with your DM so that there's no misunderstanding that the intended spell is meant as your Story Spell. If they fail to learn a spell through the master, they effectively have a second chance if the master provides them with a Spell Scroll for it.

Rules about "Level-Up Spells"

Upon level-up, most casters typically learn additional spells, the DM will attempt to weave these into the narrative somehow. If an opportunity during the story for a PC to study such a spell in a creative way, the PC could gain access to such a spell a bit earlier than normal! The DM can sometimes offer a particular skill check to gain access to the spell earlier than normal. But even if you don't gain access to it earlier, don't worry. You'll get it at the level-up.

Clerics, Druids and Paladins don't 'learn' spells, but gain all their new spells once available.

Spell Books (and Copy Shops)

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 a 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.

Spell Scrolls

A wizard spell on a spell scroll can be copied just as spells in spellbooks can be copied. When a spell is copied from a spell scroll, the copier must succeed on an Intelligence (Arcana) check with a DC equal to 10 + the spell’s level. If the check succeeds, the spell is successfully copied. Whether the check succeeds or fails, the spell scroll is destroyed.

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.

The gold cost only counts on a success.
The time is always consumed.