I'm thinking that maybe it would be like base Thaumaturgy, except with the ability to finish/cast the spell later--sort of taking the circle with you to cast the effect at a later date. The problem, though, is I can't figure out how to limit the amount of power you could put on the Runes that you take with you.
Maybe divide it like that way? Static runes and portable runes? Static runes (like her Wards and Living Lightning) work like the usual Thaumaturgy, and can hold more power because they're rooted to something, but portable runes have a lower threshold for power?
Let me see what I can come up with...
RUNE MAGIC [-4]
Description: A long time ago, Odin stabbed himself with a spear and hanged himself from The World Tree as a sacrifice to himself. By doing so, he acquired the power of Rune Magic. Now Odin gives some of that runic power to his Valkyries, making them able to serve him better. These runes can be inscribed either on static structures, or on smaller plates for the Valkyrie in question to use in the field.
Sponsor: Rune Magic comes from Odin, greatest of the Aesir and master of runes.
Agenda: The agenda of Odin is not entirely clear, but it definitely includes making preparations for Ragnarok. Users of Rune Magic might be called upon to find new Einherjar for Odin's armies or to gather weapons for the final battle.
Evocation:
Thaumaturgy: Rune Magic allows for the user to use Thaumaturgic rituals to create rune effects, provided the target of the effect is in proximity to the rune. The runes may be always-on (such as with Wards), or single use effects, after which the rune must either recharge or be reforged. Portable runes take up Enchanted Item slots and are treated the same way.
Evothaum: Portable runes can be used by an evocator as fuel for a spell, provided the spell is in line with the original design of the rune--a rune for a veil may be used to fuel a disguise spell, for instance, but not a fireball, and vice versa. The Evocator would not incur the initial mental stress for this spell, as the power, equal to the shifts in the rune's effect, is coming from the rune, but would have to make a control roll and potentially incur backlash or fallout.
Extra Benefits: Because the magic is held in the structure of the rune, a Rune Magic user does not hex technology absent of other spellcasting powers. Additionally, Rune Magic provides a +1 to the complexity of any runic effect.