Halo of Singularity - Auspex Temporal, True Perfecting Blade, True Nullity. The bearer constantly exudes a world-state paradigm whereby all effects beyond the baseline capabilities of one's form can only be achieved by skill or technology, but the potential of the latter is wholly unbound.
Alright, let's do some theorizing.
First, let's record factors we believe are relevant.
1. We need a way to find Dien.
2. We don't know a Grace that can do this.
Therefore: We need a custom grace of surpassing potency.
Therefore: we need the singularity halo.
3. We need to use the singularity halo.
4. To use the singularity halo we need to use Skill and Technology.
What is Gisena proveably skilled at?
Gisena acquired her Reneisance woman advancement by combining the Foremost runes with her graces and generated a meta-singularity.
That is, her skill with magic allowed her to utilize foremost technology to generate an effect (pseudo-retinue derived from a glimpse of Progression, this is a very high tier feat).
5. We want to use Gisena's skill with Grace magic and the technology of foremost Runes.
That doesn't seem like enough though, Dien is somewhere close to intra-galactic in scale. Can we give Gisena access to a resource of comparable scope and power?
6. Hunger could manipulate stars and constellations in the Realm if Evening.
7. Dien utilizes stars for his exponential scaling.
Theory: if Gisena (or Hunger in accordance with her directions) shaped foremost runes by generating such constellations in the Realm of Evening, she would be able to scale up her technology (runes, Realm of Evening manipulation) and skill (Grace and Rune use) to a realm comparable if not exceeding Dien. The unbound potential of such a Grace or Effect would be able to find Dien, or do something equally useful.