hollow vine
The theories behind the first 3 are based on dialogue and outfit descriptions, largely. Like Meredith's magic suit, Ming's cowgirl set. The Celestia theory is based on some of her later dorm dialogue mentioning her and the Navigator seeing each other sleep. It was written in a way it didn't sound like us finding her passed out from exhaustion.
The sisters theory is inspired by Leona being the only new character to feature an existing in her trailer as well as similar outfits, eye color, and I thought Leona's cat-like name was a hint too. I swear I heard Michele mention a sister in a multikill line, but others think that was just Madelina referencing Galatea.
Audrey's is inspired by her admission of being bad at communicating and expressing her feelings in the New Years event where I'm definitely overreading with my own autism.
Everything else is inference or just bat-sh*t crazy.
crimson thunder
last pendant
clear acorn
tepid stone
thick obsidian
tender canopy
lusty ore
potent halo