Do black cubes tier up item potential from Unique -> Legendary at a rate of 2x or higher than red cubes? I'm trying to understand which cubes have better value for upgrading item potential tier at this specific level, so I know which cube to spam during Double Miracle Time.
I've looked around the forums for the answer, and a lot of people say black cubes are the way to go, but a lot of them have never actually tried red cubes, and are just scared of that one video where a guy spends a ton of red cubes without tiering up from unique -> legendary. It'd be nice to have an unbiased answer from people who have used a large quantity of both at the unique tier. Thanks in advance for your help!
Also, there's a myth saying that black cubes give the second and third lines of your potential a higher chance to be primary (as in 12% instead of 9% at the legendary tier). Can anyone confirm or bust this myth?