I just reached Lvl50, was excited to try out live arena - and realized it needs some (muuuch) love to really work out. I was actually surprised to find many similar posts of bad experiences from gold tier as I had from bronze tier. In other words: It is all bad right now.

So here are my 2 cents for improvements:

A) Chosing heroes taking turns is currently totally insignificant imho. Just speed this up by allowing picking the heroes upfront and then let the other player remove one. That block-a-hero mechanic is a good one. Should be kept. Also, knowing which heroes the player wants to field would help the match making find a good opponent.

B) To speed up the picking of an aura, add a small menu to the setup screen to pick an "aura priority" for the team. That way you can pick the aura right at the beginning (even before match making needs to start) and it does not cost additional time.

C) Add a button "forfeit" right at the setup screen. Do not make a player enter a battle if the setup already shows it is worthless to play that match because of a totally imbalanced roster.

D) Make "Auto" active by default, or offer a checkbox for "Auto-Battle active" in the startup screen.

E) Make it possible to "communicate" to the other player that you have activated "Auto" (could be a white glow around the button for example)

F) Add button: "Let's Auto". Maybe both players just don't want to invest more time or the odds are clearly in favor of one player but you want to fight to the end - think of it as a "soft forfeit" (difference to normal auto is, you cannot disable auto mode anymore till the end of the battle). 

G) Add button: "GG". This should represent a more graceful end to the battle than just the "cowardish/rage-quit-alike" exit as of now. Give the opportunity to admit defeat, shake-hands. This is more of a GUI polishing really. The effect may be the same as it is right now. Maybe, if the other also gives a "GG" then there is a small reward for the defeated? (siehe next section H)

H) Add a possibility to share rewards after a match. For example: If you win, make it possible to give 0-100% of the win to your opponent. Some matches are really at a tie (they should be, otherwise they are just imbalanced/unfair) and at least a 50:50 share would be in order. Foster good sportsmanship!

I) Make it transparent if you do not find a match and have the player fight against a bot. Maybe give them a list to chose from which hero setup or max level would be okay. Right now it is ridiculous to have those imbalanced insta-death matches against much higher level teams.

Improvements to the match making:

(1) Let the player set a level limit at which they are willing to play upfront. For example: Rank 5, Level 50 or Rank 5 Level 22, etc. If a player has set its limit to Rank 6, Level 60, Awaken 6 and Ascended 6 (You can even refine this by allowing a limit for gear level as well), they will not be matched with someone that has set lower limits (or they are only allowed to pick heroes within the lower limits; maybe it is needed to be able to define a lower and an upper limit at which one is willing to play). I mean - this requirement is a totally basic must-have to a fair match making. As it is now, it is just non-sense, imho (what is even matched? Player level only?). 

(2) Add a mode that says: "Only same heroes". That is, the match making algorithm will only allow heroes that are present on both sides (still, the players pick which heroes to field taking turns (at this point it makes sense taking turns) and the other player has to field the same hero; maybe chose which one if duplicates exist, otherwise this can be automatic). That way the match is more like: "My build against your build". That at least is _somewhat_ balanced. Better than "My frickin awesome mythical-level-60 all-star-maxed-out team against your all level 50 not even fully booked and semi-cool geared team, just because our arena tier and player level is _almost_ the same". And this arena mode would give a chance that also some other heroes in the roster will become significant "Let's see if my Zephyr Sniper can beat yours etc."

Additional info: "Why chosing heroes taking turns isn't worth it right now"

Mainly a player will field their strongest heroes, regardless of the other team. At least this is true for the lower tiers. The roster has maybe only 5 "worthy" heroes for arena anyway at this point, so it does not matter what the other player has in his team, I cannot go higher. There would have to be a need to pick a lower leveled hero, but this has to be enforced by the game mode, as I described above in (II). Being able to react to the picked hero of the oppenent only makes sense if I have options to chose from.

Also in later tiers it makes no sense to put a certain hero against one of the opponent's specifically - it will most likely get blocked in the next phase, if the player knows it is a noteworthy counter against his/her tactics.

If something like a "micro matching" of heroes is needed, the turn-taking should be done like this: Each player presents two heroes and the other blocks one of them, then continuing with a nother pair until the team stands.