So IMO the Relic Keeper is great. I use mine to farm everything He was worth getting to 6 starts vull Ascend. Im working on Saurus now for farming however he requiers really specific gear at higher levels. Athel is also really good as she can be used on CB. But probably by far ever above the relic keeper is the Apothacary, that was a great pull.

So I will break it down by area:

Your best arena toons are Relic Keeper (RK), Elhain, Athel, and Apothecary.....RK will be the best until mid gold tiers, by then all of them start to drop off except maybe apothecary.

Your best campaign farmer are RK, Elhain, and Athel....RK is absurd at campaign, but hes just a bit slow for end gamers because of no AoE, but he doesnt need life steal gear, just needs crit/crit damage and maybe some health. He is one of the tankier attack style champions.

Your best dungeon toons are Athel and Apothecary

Your best clan boss toons are Athel and Apothecary. athel with books has a 75% chance to weaken for two turns on her default skill. That is really awesome. 

Mind you with excellent gear, saurus is a great campaign farmer, but not in the near term for you.

There are several champions that you have that are useful. Spirit host can remove debuffs which is great for arena,  void dungeon, and ice golem. It has uses against CB and dragon as well. Whisper with excellent gear is an excellent CB nuker. 

Here is my advice, concentrate on relic keeper, elhain, athel and apothecary for now. Just try to get them to 50 and then pick one to raise to 60. In fact, you can leave 3 of them at 40 and just grind one out to 60 first.Pretty much just work on that. All four of those are usable for a very long time in the game, apothecary and athel especially. Once you gear RK, in arena in silver you will do a lot of one shotting on kael/elhain/athel. In fact, a very viable strategy for arena sub gold 2, is just building teams that counter kael (being force/red is a large part of that). By the time you get your first 60, you will have more toons. Remember to watch the market for blue/ancient shards. Buy then no matter what. Wait for the next double chances event and only blow blue/purple/orange (ancient/void/sacred) shards during double events. In a month you will have a decent number more epics and if you are lucky, a legendary or two.

You will start getting skill books if you haven't already. Do not use the epic or legendary ones. That was my biggest mistake. Put all your rare ones into Apothecary. You will get tons of them. Do not use your epic and legendary books....I know I said that twice. 

Regards,

Damn, exactly what I was lookin for.. Guess I better get grinding.