Muramite Runes - OoW Spells
Collecting spells for the Omens of War expansion works vaguely similar to how it does during the PoP expansion. Though, unlike in Planes of Power there's now a Spell Rune for every single level rather than one item that covers multiple levels. You may notice that there are 6 items listed below though and not 5, that's because Ancient Muramite Runes and Glowing Muramite Runes are both for level 70 spells.
The Ancient Muramite Runes come from raid targets while the rest of the runes drop from named enemies in Omens of War group content. Once you have one of these runes in your hand you'll want to head over to Dranik's Scar where you'll find Karsor the Mad in the southern portion of the zone. This NPC is shown in my screen shot above.
For those unaware of what Muramite Runes are used for what level... Here's an easy to read format to better explain all of this to you.
Ancient Muramite Rune (Level 70 Ancient Spells)
Glowing Muramite Rune (Level 70 Regular Spells)
Greater Muramite Rune (Level 69 Spells)
Muramite Rune (Level 68 Spells)
Lesser Muramite Rune (Level 67 Spells)
Minor Muramite Rune (Level 66 Spells)