Well... the short answer is, most rare champs are just a stepping stone for your account. There is only a select few to get to lv 60. Usually, either lv 40 or 50 is enough to help you progress your account until you get more epics and legends.

I would recommend to search YouTube for videos of content creators as most of them have vids of who are good rares for each faction. Ash, Scratch, Boozer, and Cob just to name a few.

As far as organizing them all; when you go into the Champion screen. You can select "by Faction" from the pulldown menu. then every rarity from legend to common will be put into their faction groups. From there, you can see how many of your rares you have or don't have for your factions.

Two last things I would mention just because. Don't forget to assign your rares to your "faction guardian" to get the benefit from your doubles. Second, make sure to check your fushion screen too. Even if a rare stinks for progression, they still might be valuable to make into an epic.

The two best places to start when learning to evaluate champions are Ayumi https://ayumilove.net/raid-shadow-legends-list-of-champions-by-ranking/ and HH https://hellhades.com/raid/tier-list/

You can learn a lot from either or both.  However, you should know up front that most rare champions are not very good, and will fall off quickly once you start getting a roster of decent epics.  Very few rares should be leveled past L50, even for early Faction Wars.  Epics are a much better mid/long term investment.

The notable exceptions are:

• Your starter (unless you have a better campaign farmer), 
• Rares for early Demon Lord progression like Kael or Frozen Banshee
• Coldheart. Possibly 2.  
• Apothecary 
• Renegade for a Budget Reset toon
• Possibly a Painkeeper
• Maybe a War Maiden if you don't have a better Dec Def option
• Maybe other toons rated 4 stars or above by HH or A tier or above by Ayumi if that Faction really struggles in Faction Wars.  

And, honestly, that is really it. Don't waste the resources. At your stage of the game, levelling rares for only one DT Secret Room is not a good payoff on the investment.  

I collected all the DT legos years ago, and never bothered to build enough HP Rares or Spirit Rares or Magic Rares to clear those three secret rooms.       

Ok, thanks guys, that was helpful.

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