In order to get to Silver Arena, I think it is best to have at least 1 level 60 hero.
The level 60 hero will be your damage dealer.
You don't have a level 60 hero at the moment.
I think you will struggle to reach Silver in your current state.
What you need to do is focus on Campaign till you have a 6 star champion.
You need to level up food champions to be sacrificed to make a 6 star champion.
(Don't sacrifice any of your Epic or Rare heroes as food - You will need them later)
Level up Common or Uncommon Heroes
You have 3 heroes in my opinion which could be very strong damage dealers.
- Lua
- Pitiless One
- Athel
Each 1 of the above hero's offer a different strength:
Lua is the best Arena Nuker because she hits the strongest out of the 3.
Pitiless One is the best Campaign Farmer/Nuker because he has built in Healing + C.Rate Aura.
Athel is the best Clan Boss Nuker because she does the debuff Weaken.
All 3 of these heroes can be Campaign Farmers.
All 3 of these heroes can be used in Arena as a Nuker.
All 3 of these heroes can be used in Dungeon's as a Nuker
I have already told you there strengths were they excel at.
The decision on who to 6 star first will be up to you.
Pick the hero you like out of the 3.
Level the hero you pick to level 60.
Than come back to the thread and ask for help in Arena when it is done.