Core Aura linkskill?

it really makes me wonder if it's better to just use dusts from drops considering it took at least 5 times(pink goes back to green then goes back to pink,100 cubes) from pink>gold, it's basically confirmed that it can drop ranks, Idk if it can drop from green>blue I just know it can drop from pink>green

Yes, its actually smarter to only use stardusts on your core aura until it reaches gold rank. I bought the 300 nx supernova dust from cs because i believed they couldn't drop your rank. The possibilty of rank decrease is mentioned on the stardust description but the not the supernova dust one It took me about 30k nx worth of supernova dust(100 cubes) to go from blue->gold rank( had several pink->green rank drops along the way). Theres condensed supernova dust in cs for 1.3k nx, it alters the core aura stats but cant increase or decrease ranks so thats the only safe way to change your core stats once it reaches gold rank