I believe that there is a benefit to taking Frenzy over Rending; that being the 2x multiplier from Frenzy for further Astrology progress. Admittedly, I'm a bit iffy on whether on whether 'All subsequent progression in that field is made faster and easier' bit would apply to unravel the mysteries of the Impossible Perfection, or if that just applies to grinding up skill level, but if it does help with Impossible Perfection then throwing another multiplier on there would be quite huge.
You'd already have a pretty wild x10 multiplier and a x2 multiplier on Impossible Perfection isn't much compared to spending 25 Gnosis on it. Consider how many Excelsiors would be required to match up to a single Eternal [Subject] Mastery, for example. Especially given how immediately you'd need those benefits.
The Goal of All Life Is Death
Thinking about other builds.
[D] Plan Recursive Empowerment
-[D] Heavenly Sovereign (Permanent Self-Enhancement Magic)
-[D] Supernova Attainment
Given the description of Supernova with regards to Dark Arts i.e. that we could execute basically any illegal effect, despite our middling DA skills, I'm inclined to believe it allows us to cast anything that our Magical Power could cast, as long as it falls within our Domains of Greatness. That being the case, picking this option opens up a recursive self-improvement loop, where we can execute all the rituals Geist used to empower himself without actually needing the relevant magical skills to learn them, thus unlocking more rituals to execute. Given the relatively narrow scope of this Domain, I don't think it would be disempowered in the way that a Domain like Spells would be. With that in mind, we could open up bonuses from Transfiguration, Occulemency, Potions and Alchemy, to unlock more and more and more improvements to make. By the end of it, we'd might be able to punch out a giant physically and cast at the absolute peak of human potential magically. We'd still need the skills to back that up, but honestly, raw power can make up for a lot.
This is even better than it sounds, since we'd be able to achieve effects that would otherwise be impractical or morally abhorrent to achieve, like some rituals that would require the sacrifice of a thousand people, since we're just actualizing them through sheer willpower. It's probably got somewhat less absolute long term potential than the Singularity build but skipping ahead of the curve like this opens up so many new opportunities that could make up for it.
Alternatively, take Apparition as the Domain instead, perform DA self-enhancement, and then see if we can't make our way to the Celestial Realms for all the sweet loot there anyway.
What a caveman strategy!