Met the best SA at the beauty supply store. I told her she should create a blog about coloring hair, she explained everything so clearly for once.
She told me I have an ashy base that lightens to a honey color, so I can choose either undertone to enhance my hair color. A cool toner or glaze will look more natural on me, and a warm one more striking. There was only L'oreal Casting Creme Gloss (a semi), and similar formulas to choose from. Hoping for something less strong, so I will ask at a salon as well.
For those interested in Casting, if you want to enhance your natural hair color, first match your hair color to a box, and then go for the corresponding lighter shade. (Not necessarily the lighter shade in terms of number, but also in tone.) For example, 713 Iced Beige is a close match for my hair, so I would use 810 Pearl Blonde. It won't come out that blonde, but add more dimension to my hair. If I used the Iced Beige, the result would be too dark.