A rune scribe masters the secrets of the runes of power – ancient sigils that embody the fundamental magic of creation. Rune magic is exceedingly rare: some of its secrets have been lost, and what lore remains is jealously guarded. Few rune scribes share their lore with others. Indeed, most rune scribes take on new students only if doing so allows them to gain access to a forgotten or missing rune.

Source: Unearthed Arcana 9 - Prestige Classes and Rune Magic

You must meet certain prerequisites, listed below, in order to multiclass in or out of this class.

The Rune Scribe Spell Slots per Spell Level
Level Features 1st 2nd 3rd
1st Rune Lore, Runic Magic 2 - -
2nd Runic Discovery 3 - -
3rd Runic Discovery 4 2 -
4th Living Rune 4 3 -
5th Rune Master, Runic Discovery 4 3 2

Prerequisites

Dexterity 13. Rune scribes need agile fingers to master the intricate patterns of a rune.
Intelligence 13. Rune lore requires intense study and knowledge.
Proficiency in the Arcana skill. Rune mastery requires an understanding of arcane lore.
Character level 5th. Rune magic awakens only for powerful souls, and you must be a 5th-level character before you can gain levels in the rune scribe prestige class.
Complete a special task. You must find a rune and present it to an NPC rune scribe who accepts it in return for tutoring you in the ways of rune magic. You cannot gain more levels in this prestige class than your tutor has. You might need to seek out additional runes and present them to more skilled rune scribes in order to reach 5th level in this prestige class.

Class Features

As a rune scribe, you gain the following class features.

Hit Points

Hit Dice: 1d8 per rune scribe level
Hit Points at 1st Level: 8 + your Constitution modifier
Hit Points at Higher Levels: 1d8 (or 5) + your Constitution modifier per rune scribe level after 1st

Proficiencies

Tools: Calligrapher’s supplies, mason’s tools, woodcarver’s tools
Saving Throws: None
Skills: None

Equipment

The rune scribe prestige class does not grant any special equipment.

Rune Lore

At 1st level, you learn the basics of scribing runes, and are able to activate a master rune’s full range of properties when you are properly attuned to it. The Rune Magic page contains information on master runes and descriptions of runes and their properties.

The first rune you master is the rune you found and presented to your tutor to qualify for this prestige class. Your entrance to the class includes the process of mastering that rune’s secrets.

Runic Magic

Runes can make use of your own magical power to augment some of their effects. You gain a number of spell slots as specified on the Rune Scribe table, but this prestige class does not grant spells known. Instead, as a rune scribe, you can expend your spell slots to empower runes, as described in the “ Rune Magic ” section.

For the purpose of multiclassing, to determine your total spell slots, add your levels in rune scribe to your levels in classes that grant you the Spellcasting feature. For example, if you are a rune scribe 4/wizard 6, you would have the spell slots of a 10th-level character, in addition to having the cantrips and spellbook of a 6th-level wizard.

Runic Discovery

Your continuing study of runic magic allows you to recreate the secrets of new runes without first needing to uncover them. At 2nd, 3rd, and 5th level, choose a rare rune. You can attune to that rune even if you do not possess the master rune for it. (See the “ Rune Magic ” section for information on rune rarity and master runes.)

In order to attune to a rune in this manner, you must spend a short rest doing nothing but meditating on the rune. At the end of the short rest, you are attuned to the rune. You are considered to always have the rune on your person for the purpose of determining whether you can use its features.

You can spend another short rest doing nothing but meditating on the rune to end your attunement to it.

Living Rune

Runes are a part of the living world, and your studies allow you to connect to their magic in increasingly powerful ways. At 4th level, you learn to incorporate rune magic into your identity, allowing you to augment your body and mind.

At the end of a long rest, you can choose to increase one ability score of your choice by 2 or increase two ability scores of your choice by 1. At the end of each subsequent long rest, you can alter this choice, reducing the scores you previously increased and improving different scores. (If you chose to increase two abilities, you can opt to alter only one of those choices.)

Rune Mastery

At 5th level, you attain the ability to master an ever-greater range of runic magic. When you attune to a rune, you can choose to have it not count toward your limit of attuned magic items. You can be attuned to only one such rune in this manner at a time. You can use this ability again after you end your attunement to a rune.