See title. I’m having trouble deciding, Mystic Ray is a great assist, and I want to use it to the best potential. I’m thinking characters like Viewtiful Joe use it pretty well, but it looks really good with rushdown characters, it lets them convert off of alot.
It’s not a good keepaway assist. . . not at all. Good keepaway assists either have a lot of durability, quick speed to beat a lot of options, or provide a lot of hitstun/blockstun to allow zoning characters to gain momentum. Mystic ray is not scary from fullscren. If you get hit by it, there is a 90% chance the person won’t have the screen advantage to combo out of it. If people are going to insist on continuing to overhype this assist, at least use it how it’s meant to be used, which is for rush down characters.
Ghost Rider 
rushdown…just hope you aren’t rushing down someone with projectile-nullifying moves or armor moves etc…you will get blown up trying to rushdown dormammu with it etc
Surprisingly, I feel Keep-away characters.
It makes arthur pretty damn solid because it cuts off some of the vertical axis making super jumpers less of a problem for him.
I believe Shuma would help Hawkeye out a lot. It keeps them busy while his vertical axis zoning moves get started up.