There should be a building called the ARENA
The raid menu can be accessed from there, and the classic based on raid trophies raid will be renamed to “Ladder”.
Make a new style of raid called “Arena” which would have the following Team Power Ranges:
up to 2000
2001-2999
3000-3999
4000+
Every month the players with the top 100 Arena trophy count in each range will get prizing.
Note that Ladder trophies are separate items and the classic ladder raids will still exist.
The reason I suggest this is every player levels up their heroes individually, but once they get a new shiny 5* hero, it takes a very long time to get it leveled enough before you can even really start using it in your main lineup.
However if there was raid areas then you can make up teams in different TP ranges and use them the whole time your leveling them up.
- It would open a whole new strategy to the game as now its not just your most powerful team (defense team) that matters, but you can have a full roster of teams designed to excel in a specific power band.
- Being ascension stuck will be less of an issue since a hero at 3/70 might be optimal in a lower difficulty setting.
- players would use their heroes at all levels of experience, not just maxxed
- It would promote buying more team spaces in your roster.
It would introduce a new play style and defense formations, eg
supertank: 1 maxed 5* and 4 unleveled 3*'s is below 2000, but would be a challenge to a regular 5 man team at 2000 TP. To be more annoying, put the 5* in a corner, and use 4 belith or brienne 
Other team layouts with 3 or 2 max heros and leveled filler just barely fitting into the upper end of a power band might be a valid strategy, of course depending on what heroes used.
