Unfortunately all that would really do is encourage people to build the wrong champions. There are literally no common champs you should ever be leveling, and there is basically only one uncommon champ worth leveling (Armiger). Even the rare pool is extremely weak, and should be leveled extremely selectively (generally speaking, only your starter champ and a few very specific rares such as Coldheart and Frozen Banshee)

Hmm, my initial thought:

I make a new account. I am superlucky and pull a good legendary early on. 

Than I see: You are not allowed to use this in arena. You need arena to be advancing your Hall and get boni. 

I would ask myself....why does the game punish me for getting a leggo...why can't I use it to progress in arena?

I didnt think of that,tyvm Matrim

This is actually one of the bad things Raid does, forcing you to build champions that you most likely will not use anywhere else. Currently we have secret rooms of doom tower. I was "force" to build 3 to 5 rares  just for one room. I say I was forced because I need to clear all secret rooms to get Ramantu. Outside from that one room and one mission, these rares will not help me in other content. 

In faction wars, I can clear some stage 21 floors with only 3 champions. But in order to 3 star it, I needed to build two more. Then after I 3 star that stage, the other two champions are again will never be use. Another waste of resources. 

Now suggesting to use common, uncommons and rares only in arena, is such a bad idea because of the reason I mentioned earlier. 

I  think  I  gave  a  similar suggestion  to  the  game  2  and  half  years  ago.

The  game  never  did  it,  but  I  still  love  the  idea.

I  will  give  you  and  upvote.

I  hope  the  game  implements  the  idea.

I  also  want  to  add  the  game  should  have  level  restrictions as  well.

For  Example:

Bronze Tier 1  -  Only  Level  30  or  below  Rare,  Uncommon,  or  Common  are  allowed

Bronze Tier 2  -  Only  Level  35  or  below  Rare,  Uncommon,  or  Common  are  allowed

Bronze Tier 3   -  Only  Level  40  or  below  Rare,  Uncommon,  or  Common  are  allowed

Bronze Tier 4  -  Only  Level  45  or  below  Rare,  Uncommon,  or  Common  are  allowed

Personally, i cannot see any problems with Arena bronze and silver. Both my recent accounts, are in Arena silver-3. One is ca. 40 days old (team of Spirithost, Kael, Ninja, Diabolist) other is ca. 15 days old (team of Kael, Ninja, Warmaiden, Diabolist). And i am not in silver-4 only, because playing without defense.

Essentially, your idea would mean that no one could use their Ninja till they hit gold.  A lot of people recieved Ninja at day 7.  It also means they could not utilize thier Shaman or HK till they hit silver.  At day 7 every one has at least one epic (if not Ninja) and it generally takes a bit longer than 7 days to hit silver.  Basically I see this as actually making it harder for newer players to progress, I mean, if they're not allowed to use their champs?

Shieldguard is okay, too, but I'd only take him to 60 if I completely ran out of other stuff to do.

I apologize ALL,had a funeral to attend. I was looking at the basis of your opponent,they dont get to use any lego's themselves,so its not directed for what you will do. My idea is not a fix, but arena needs a change. If I went into arena with this format, I would sure feel better looking at more teams equal to my team then looking up and getting one win here or there,if at all. There are days where i just go and lose 5 games to do the daily's. I see a team 95k in bronze one, there are so many like this,so tell me how fair it is for a new guy or f2p to go against a lot of higher power and speed teams without the gear or champs. I am not trying to ram my idea at anyone. Just tired of seeing so many people mad at arena. I gave an idea,best I can do. All I was trying to do was level the play field. I would love to here your idea,maybe you have the answer,but until we ALL get together on a good idea we ALL love,the winner will always be PLARIUM. 

Sincerly Voompyre2

I  think  making  Rarity  Restrictions +  Level  Restrictions would  help  shake  up  the  Arena  Meta  for  the  lower  Arena  Tiers.

A  few  of  the  other  players  did  mention  the  negative aspects of  having  such  restriction.

However,  it  will  have  positive aspects  as  well.

Players  will  have  to  rely  more  on  skills  vs.  Over  powered  heroes.

In  the  Arena  map,  there  are  three  areas.  Two  of  them  are  already  being  used,  the  Classic  Arena  and  Tag  Team  Arena.  The  last  area  isn't  being  used  and  is  nicknamed  'The  Pinnacle.'  I  would  like  to  see  this  come  into  the  game  perhaps,  but  not  to  the  current  system.  It  should  be  it's  own  area,  with  unique  rewards.  Maybe  you  can  get  a  boost  in  the  other  two  arenas,  or  get  tokens  to  transfer  medals  into  gold  bars  and  such.

Early game players already have limited rosters and are encouraged to max out a small number of champs

Forcing them to build more champs that are specialised to one area doesnt seem helpful to them to me.

Depends  on  how  you  look  at  it  Trevor,  Let  me  give  you  an  example.

Lets  say  your  a  new  player  with  limited  roster  and  the  game  has  restriction's.

Lets  say  the  restriction is  level  30  heroes  +  rare  or  below.

How  hard  would  it  be for  a  beginner to  have  a  hero  reach  lvl  30  vs.  lvl  60?

How  wasteful  does  it  sound  to  you?

You  level  up  4  heroes to  complete in  arena  only  lvl  30.

Later  on  down  road  if  you  don't need  them  anymore,  you  can  use  them  as  chicken.