The Arcane Scroll is an item added by Better With Mods. It comes in 30 variants, one for each enchantment and curse in the base game, although the curse variants aren't obtainable yet. The scrolls can be used in the Infernal Enchanter to enchant items. By default most scrolls are obtained by killing certain mobs and the rest are obtained through villager trades. Bosses have a 100% drop chance for scrolls. Looting will also increase chances of getting a scroll.
Mob
Enchantment
Bat
Feather Falling
Blaze
Flame
Creeper
Blast Protection
Endermen
Silk Touch
Ender Dragon
Sweeping Edge
Ghast
Punch
Guardian
Depth Strider
Magma Cube
Fire Aspect
Zombie Pigmen
Fire Protection
Polar Bear
Frost Walker
Silverfish
Efficiency
Skeleton (While in Nether)
Infinity
Slime
Protection
Spider
Bane of Arthropods
Squid
Respiration
Witch
Aqua Affinity
Wither
Knockback
Zombie
Smite
Villager
Enchantment
Butcher
Sharpness
Farmer
Looting
Smith
Unbreaking and Efficiency
Priest
Fortune
Librarian
Power
Fisherman
Lure and Luck of the Sea
By default, Arcane Scrolls will be dynamically generated to add other modded enchantments, which can be obtained through Villager trades.