What about Legion would you change in order to “fix” it in your eyes? And, if you could, go into detail about that change.
For example, I would definitely redesign the legendary system. No one likes the RNG, I would make it so that each legendary you got FELT legendary, and not everyone had two.
An idea I had was make getting a legendary (still have a few legendaries per class, but you can only target one), a longer process a la MoP or WoD. Perhaps you had to work with Odyn or Kalecgos, and make it similar to the Balance of Power questline where instead of forging more Power for your artifact you created a legendary. Something that gets rid of the asinine RNG
I didn’t find the right solution from the Internet.
References:
http://www.mmo-champion.com/threads/2200785-How-would-YOU-fix-Legion
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