With a team of Kael, Warmaiden, Apothecary and Sinesha, I'd think you could easily get to Silver 2 if not 3 or 4. The problem seems to be that your speed is not that great yet, crit damage on Kael needs to be  higher and also, he does need accuracy to land those poisons. Though that's more of a problem for Clan Boss than for the arena where most of his utility comes from that first devastating Acid Rain. 

But a team of Gorgorab (lead), Kael, Warmaiden and Apothecary might be even better. You definitely should be using Gorgorab, considering he offers speed aura for arena, AOE resurrect and heal, AND increase attack plus turn meter. Insanely good for arena. Mausoleum Mage is also a good option, but I think not quite as good as Gorgorab. Both of them would also help you a lot in dungeons (wish I had them... as well as Sinesha). 

For Clan Boss, you should be doing better than you are considering the champions you have; the important thing to know is that poison (which hits as a percentage of max HP) is very, very strong on Clan Boss. So first step, get some accuracy on Kael so his poisons will actually land. Secondly, you have Frozen Banshee - she does 2.5 to 3 million damage on her own for me with those poisons. She's also useful in a few dungeons like Dragon, though pretty useless for arena and the other dungeons, because she's a one trick pony who's insanely good with poisons but doesn't really do anything else. 

Actually, a few more things: you should probably be using Coffin Smasher on your Clan Boss team, considering that he offers HP Burn (75k damage to CB every turn that he has that debuff) plus reduce attack on his A1 - if you can keep permanent reduce attack on CB, you'll survive longer and can do more damage. I personally don't use him but that's because I have other champions who do those things instead (perhaps you do too, never mind in that case, but I didn't immediately see any). 

And I wouldn't bother taking Elhain any further. With Kael already at 60, there's little added value in getting Elhain there as well - sure, you want more high DPS champions, but you should have better options than her, preferably with different affinities, more useful to get a Force or Spirit nuker than a second Magic one. Maybe Bloodfeather, for instance. 

Well L9753 thank you for your advice! I was already thinking about Gorgorab. I think it can be used in multiple areas as you are writing and I also like the undead faction (i want a team). So I will definitely start to exp him. 

Btw. CB can be also 2.1 without auto. Anyway there is space for improvement.. Thank you for your evaluation of my stats. Honestly i did not realize Kael problem with missing acc... And yea i know the speed can be better. I think speed is the most important stat... It is reason why I am farming speed sets..
And I already using coffin smasher for CB. But he is only 40 lvl and i dont wana invest in him anymore... I would like to repace him with another poision... Yea frozen banchee she looks good and she is also from undead which i also like.. BUT is it realy worth to invest in her? I think about Corpse collector instead of her. She has 5% poision on 3rd skill and Leech on 1st. Isnt it better? I also think she is more usable for other areas.. Like keep because of heal reduction. What do you think?

I wasn't familiar with Corpse Collector, but indeed she does look good. Less poison than Frozen Banshee because of the long cooldown, but that Leech probably compensates for that... although of course she's an epic, more difficult to get the required books than it is for FB. 

For spirit keep, note that she has the wrong affinity, so she wouldn't be as good as you'd think. Considering the affinity disadvantage, she'd miss quite often, even with high accuracy and with books invested for a 100 percent chance. 

Who else is on your CB team? If you're going to replace Coffin Smasher, do you have others who can at least decrease the CB's attack? HP burn would also be nice. It does more damage than poisons, though unlike poisons you can only put one at a time. There is a maximum of 10 debuffs at any time, so you want to have those 10 debuffs on him as often as possible. Definitely decrease defense, decrease attack and weaken if you have it, then as many poisons as you can put and 1 HP burn. And I guess that Leech if you use Corpse Collector, looks very handy as well. 

I would like to solve my arena offense+defense first... I am quite satisfied with CB. My clan killing easy and half of normal and I have both best chest each time.

Soo.. My current arena setup:

1. Gorgorab

2. Warmaiden 

3. Kael

4. Apotheracy

The speed order: Warmaiden, moan, kael, apoth

Is it best what I can have from my characters now? (meanwhile I got also Galkut, but he looks terrible)

Additional question: What about my Sandlashed Survivor? She looks also good. Isnt she stronger and more variable in the game overall than warmaiden? Anyway, warmaiden have only 30% - def...

Who do you mean by Moab/Moan? I can't see any champions with that name or similar.  

Sandlashed Survivor is definitely good, but it's not like she has the same role as Warmaiden with the decrease def 60 percent (not sure where you get 30). Once you have somebody like Stag Knight, Tayrel, Madame Serris, they will immediately make Warmaiden obsolete, but there aren't too many rares/epics who have an AOE decrease defense 60 percent. 

Sorry for the misunderstanding, I already corrected my previous post. :)

My CB:

Kael, sinesha, apotheracy, coffin smasher, grappler

- I realized my coffin smasher have the worst eq. overall. I think I need to gear him up. Is it worth going from 4 stars to 5 stars for him?

I would like to prefer just gear him up and keep him for 40 Lvl for a while and focus on frozen banshee.. But who to replace? Grappler? (I think Sinesha and apo is decent support with decent heal and I do not need grappler shield anymore and his poison is also weak..)