Diana desperately needs a buff. If Diana gets behind in a game she likely won't recover for the duration because of her all in kit. Even against champs she counters, Diana won't be able to efficiently win trades. And even when she gets ahead it's hard to maintain a lead because she is a full-dive champ and is extremely vulnerable to any type of cc.
1. Make her shield CD start immediately after use instead of after all the orbs have been proc-ed. Often times, if she is running from a champ, her shield seems to take forever to CD if she hasn't used all the orbs.
2. Give her a slight CDR to her Q so that she can farm from range when she is pushed in. This would allow her to save her W incase she gets all ined.
3. Completely change her E. Put the attack speed back in her passive. Instead, make the E do a very small amount of damage or give her a slight armor/mr buff for a few seconds.
I know if she gets changed too much she will be the strongest mid in the game, but as for most of the last season and now, she is one of the weakest and has a terrible recovery from a bad start. Soooo many people love her play-style but don't use her because she is incredibly weak rn. One small tweak and she will be balanced again, but something HAS to change.