My advice? Don't try for a ranking in arena with a defence at this stage - instead look to farm the arena for points by putting up a single lvl 1 champion defence. That will keep your ranking low as others attack you, meaning when you need to attack your opponents will generally be weak, making it easy to farm for arena points. This goes doubly so for arena tournaments. 

Also, don't make building an arena team your priority at this stage - look to develop a good Demon Lord team first.

My biggest advice to you: stop playing 3 accounts at the same time! You have 0 lvl 60 champs in all accounts together and say in your initial statement, that you are a casual player. Raid is a very time intensive game. Focus your effort on one account. The hours you have spent in acc 3 and 2 should have been used to bring a champ to lvl 60 in acc 1 instead.

Develop your champs. Use ascension potions, visit the Minotaur for scrolls, make champs lvl 60. The difference between lvl 50 and 60 is not like 5/6 to 6/6. A lvl 60 champ is twice as strong as his own lvl 50 version. The fact that you could reach a stage as high as silver 3 in arena is allready surprising, if you use lvl 40 champs in your arena team (Rector). If you climb higher, you are not going to face any teams you could beat. 

There are different versions of the decrease def debuff, a small and a big one, that reduce the enemies def by 30% or 60%. Bellower has only the small version, Warmaiden the big one. Bellower is a good champ in general, but not really in arena. He is a very good campaign farmer and therefore should be your first lvl 60 champ.

Where is High Khatun? The day 30 log-in reward champ. You have her in account no. 3, but not in the others. I really hope you did not use her as food to upgrade other champs. Or did you not reach day 30 yet and she is from a shard at account no. 3? If so, you will get her for free at day 30. I asked about her, because the easiest way to start in arena is a "speed team" with High Khatun (free champ), Warmaiden (can be farmed in campaign), Ronda (free champ).

You actual team has no strategy. You just put 4 random champs together that don't really fit. The mentioned speed team has a strategy. High Khatun in gear that makes her fast, so she goes before any other champ on the battlefield does, inclduing the opponents team. She increases the turnmeter and speed of your team, so the team members follow up before the opponent gets a turn. Then Warmaiden to put decrease def (60% version) on all enemies. Last, but not least Ronda. She just nukes all enemies away with her A3 skill. That team has a strategy, and there is still a free spot for a 4th champ.