Rival Magic Potent Mythic Blood

In Rival Magic the Norse Magicians the Muspelli gain their powers from the Jotun evil norse giants the believe they are descended from. One of their abilities is a giant form, called the ettin mod, that gives them increased size, boosted characteristics, and stronger magic. In the hermetic integration section they mention the possibility of Magus with mythic blood developing their own version of this ability.

This would be perfect Virtue for a mystery cult based on mythic blood and magical genealogy I've been kicking around for a while. Anyone have any thoughts on what how the hermetic version of this virtue might work and how it might differ from the Muspelli's Ettin Mod.

You migth want to check the inner heartbeast section in HoH:TL, they do offer rules for an "advanced" heartbeast that you might adapt or base your new virtie on.