Spell scroll

A spell scroll is a roll of parchment, sometimes attached to wooden rods, and typically kept safe in a scroll case. It contains the magic of a single spell, with an arcane incantation written in a "mystical cipher" to cast it. The spell scroll itself is treated as a material component for its realization and doesn't require the caster to provide any material components.

Description
To unleash the magic contained in a spell scroll, any creature that can understand a written language can read the arcane script on a scroll and attempt to use their action to read it. The spell must be from their class's spell list, otherwise, the scroll is unintelligible. Casting the spell by reading the scroll requires the spell's normal casting time. Once the spell is cast, the words on the scroll fade, and it crumbles to dust. If the casting is interrupted, the scroll is not lost.

If the spell is from the caster class's spell list but of a higher level than they can normally cast, the caster must make an ability check using their spellcasting ability to determine whether they cast it successfully. The DC equals 10 + the spell's level. On a failed check, the spell disappears from the scroll with no other effect.

The level of the spell on the scroll determines the spell's saving throw DC and attack bonus, as well as the scroll's rarity, as shown in the spell scroll table below.

Copying process
A wizard spell of 1st level or higher can be copied from a spell scroll to the wizard's spellbook if the wizard has spell slots equal to the spell level. To copy a spell, the wizard must make a successful Intelligence (Arcana) check with a DC equal to 10 + the spell's level. Whether the check succeeds or fails, the spell scroll is destroyed.

Copying a spell into the spellbook involves reproducing the basic form of the spell, then deciphering the unique system of notation used by the wizard who wrote it. They must practice the spell until they understand the sounds or gestures required, then transcribe it into their spellbook using their own notation. For each level of the spell, the process takes 2 hours and costs 50 gold pieces. The cost represents material components the wizard expends as they experiment with the spell to master it, as well as the fine inks they need to record it. Once the wizard has spent this time and money, they can prepare the spell just like their other spells.

Campaign 1: Vox Machina

 * Before leaving the throne room of the Emberhold that was rapidly filling with lava, Scanlan read Enhance Ability (Bull's Strength) scroll, giving himself advantage on Strenght checks (in Pathfinder the ability gave +5 to Strenght modifier). Scanlan later read another scroll of Bull's Strength to Grog to prepare him for Kevdak fight, accompanied with a song. At the end of the campaign, Sam believed that Scanlan still had a scroll of Bull's Strength.
 * Scanlan expended Chain of Lightning scroll against K'Varn.
 * In downtime in Emon, Keyleth made a Polymorph scroll and gave it to Vex.
 * Tiberius used scroll of Polymorph (possibly given to him by Vex) to take shape of a gadfly and follow Hosin in the Velvet Cabaret.
 * Tiberius had two spell scrolls of Blight using one of them on a fire elemental.
 * In Emon, Scanlan bought a scroll of Hallow for 6,000 gold pieces and a scroll of Spirit Guardians for 2,000 gold. He used Spirit Guardians one in the crypt of the Whitestone Castle against de Rolo ghosts.
 * Raishan disguised as Assum Emring told Vox Machina that he had escaped from Emon and reached Whitestone using a Scroll of Teleportation.
 * Anna Ripley took a spell scroll of Gate from an altar in the cave of Glintshore, which after her death was looted from her corpse by Vox Machina. Scanlan expended Gate scroll to summon Yenk and unleash him against Vorugal.
 * Raishan read a scroll imprinted with an old version of the Speak with Dead spell to pull out information from Thordak.
 * Taryon Darrington bought a scroll of Fire Shield for 6,000 gold pieces from Cidrick Gillsman.
 * Ipkesh gave Percy a scroll of Silence.
 * Pecry found a leather tube on the sinking Tempest Fang and Tary later identified it. Tary used a Programmed Illusion scroll to create a chain devil and distract Mentiri guards.

Campaign 2: The Mighty Nein

 * Caleb bought arcane ink and fine paper from Pumat Sol to copy two scrolls he found in his journeys, transcribing them into his spellbook.
 * Investigating the Sutan residence, Caleb came across a scroll case, attempted to take it, but was stopped by Fjord who worried about compromising their robbery by stealing extra property. After the guards of the residence were distracted by the clutter created by Ulog, Nott stole the scrolls.
 * Calianna Mordsson gave a scroll of Invisibility to Nott hoping it will be helpful to Caleb who soon got it from Nott and was planning to transcribe it into his spellbook. Infiltrating the Sour Nest, Caleb reluctantly used the scroll of Invisibilty.
 * Caleb found a Protection from Energy scroll in the collapsed room of the King's Cage.
 * One of the books Caleb was reading in the Vellum Steeple Archive had an enchanted page with a pocket dimension. Nott and Jester agreed for Nott to create a diversion to make space for Jester to rip this page out of the book. Nott shot a crossbow at Caleb, aiming at the book strapped under his arm, but unfortunately missing and wounding him. Jester successfully and quietly tore out and secured the page. Caleb shared the stolen page with Essek who used Dispel Magic on it, which released two pouches and a round case. Calleb Identified parchments contained inside the case to be three scrolls: Greater Invisibility, Major Image, and Levitate. Caleb later cast two of them likely after he copied the spells from the scrolls into his spellbook.
 * Caduceus bought a locked box in Seafloor's Bounty that contained Flaming Sphere and Telekinesis spell scrolls. Since Caleb already had Flaming Sphere in his repertoire, he only took the scroll of Telekinesis, noting that he still needed to get paper and ink to transcribe it into his spellbook. Veth kept the scroll of Flaming Sphere for a single use. She read the Flaming Sphere scroll against cold snap spirits in the A5 crash site of Aeor.
 * Caleb copied two spell scrolls into his spellbook.
 * Cree expended a scroll of Control Weather to create a snow bridge across the River Inferno.
 * Veth asked Allura for a Intellect Fortress scroll to protect Caleb, which Allura gave her soon after.
 * Yussa had a Plane Shift scroll created for him by Planerider Ryn in case of an emergency. When Yussa was unreachable while investigating Cognouza in the Astral Sea, his assistant Wensforth broke the scroll case with the Plane Shift scroll and gave it to the Mighty Nein to escape Nicodranas fleeing from Trent Ikithon.

One-shots

 * Tary used his scroll of Fire Shield he bought from Cidrick Gillsman in Vasselheim.
 * Gryffin Earandil had a Feather Fall spell scroll, but had no opportunity to use it.
 * During their non-canon adventures with Lucky Jack, Beau and Yasha found a spell scroll of Dispel Magic.

Shops

 * The Invulnerable Vagrant has these spell scrolls that were bought by Caleb: Shocking Grasp (75 gold pieces), Shield (200), Hold Person, Feather Fall (100), Expeditious Retreat (100), Catapult (100). These spells are in the shop's inventory but haven't been purchased by players: Wall of Ice, Arcane sword, and Cloudkill (6,000).
 * The Temple of the Mentor sells: a spell scroll of Detect Magic (10 gold), a spell scroll of Divination (125 gold), and a spell scroll of Commune (250 gold).

Trivia
The 5th edition Dungeon Master's Guide has a scroll mishaps table with various aftermath effects for the creatures who failed to cast the spell from a spell scroll and failed a DC 10 Intelligence saving throw thereafter.