Runes for Dummies: Arcane.
Runes for Dummies: Arcane is a book found in the Chamber of the Guardian of Dalaran during the quest 
[45] Dabbling in the Demonic.
Content[]
Runes for Dummies: Arcane
<Among many large, colorful diagrams, you find an entry on one of the runes present in ritual circle.>
A very common rune used to empower arcane rituals is Talar.
This versatile rune can be used in most incantations; however it is rendered inert by void and corruption magics.
Patch changes[]
Patch 7.2.0 (2017-03-28): Added.