Quote Originally Posted by weras View Post

We should also mention the Sacred crystals, and that you should keep a handful around for stamina and charisma restores for events, and if you want to throw them away, the premium roll is the only one that's worth it. The unit odds according to jp wiki are approximately
50% silver
37% Gold
10% Plat
3% Black

while the rare one is
70% Silver
26.5% Gold
3.5% Plat
1% Black

Keep in mind that you may be unlucky and never get anything other than Eunice and Mortimer though. You can also get extra silvers from the 2k gacha (~3.5% so like 1 in 32 rolls) but you really shouldn't rely on it if you are in need of a specific one.
Thanks for this info. I'm still pretty new to the game, thought to CC a healer first so got my strongest one to 50. But I have been struggling to get a copy Silver Healer to complete any CC. I guess the best way for me to get Silver Healer without Sacred crystals is a lots of gold and 2K Gachas. If there is another method for getting Silver units to use in CCs I'd love to know.