Yellow Diamond

That's one of my inspirations (fitting, considering Sailor Moon was my first anime and holds a special place in my heart).

Mine too! You can't go wrong with Sailor Moon if you're looking for magical girl inspiration.

Granted, a lot of inspiration is taken from the darker takes on the genre too, but I plan to balance it out with plenty of comedy and lampshading of tropes (one of the first jokes I came up with was a bit of commentary on fanservice, with Spike outright admitting he has no clue why this happens in transformations, but they'll get used to it).