I had an idea for a tradition of celtic mages that use ogham script for rune magic similar to the viktir joining house miscellancea. I'm wondering what kind of major supernatural virtue can I give them to represent this magic?
They know full well about verdictus attitude on having other item enchanters in the order and have chosen to conceal their runic powers for the time being.
Not rune magic as such, but there is already a tradition of celtic magi using the ogham script.
See the Damhadh-Duidsan (RoP:I p137-138)
Not quite what i'm looking for it seems to focus more on their linage with giant blood and the supposed ties to the infernal with incantations. Nothing to really do with rune magic.
Really I'm wondering what kind of virtue you'd give to rune mages in general if they joined the house. Like say viktir or the anglo saxon rune magi. What supernatural virtue would scream rune caster?
There isn't really any good rune virtue. Rune magic is too versatile to be compressed into a single ability.
Better to have some supernatural virtue or ability that provides for some aspect of what is special with rune magic.
The hermetic flaw should be obvious though - Necessary Condition (Runes).
A variant of Mercurian Magic, with the assumption that they have to scribe the runes as part of the Rituals. You knock the "Can't do spontaneous magic" down to just "can't do Fast Casting" because they have to trace the runes on SOMETHING to cast them and you just can't do that in only 2 seconds, and add the Necessary Condition (Runes) as Erik T says, although I would clarify it as Necessary Condition (needs a surface on which to write or carve runes)
Note Mercurian Magic has been errataed (as part of what we later learned was the balance pass for DE). Now "[a]ll known members of the Mercurian lineage also have the Minor Flaw Ceremonial Spontaneous Magic", instead of the trouble with spontaneous magic being an inherent part of the Virtue.