You should use Frozen Banshee instead of Kael for CB, she's a far better poisoner. Although if Kael already has warmaster, you maybe want to wait until FB does too, that obviously makes a big difference. I'm also not sure about Catacomb Councilor for CB - yes, his ally attack is of course great, but is he worth taking up a slot for one ally attack every 4 or 5 turns? Zargala or Rearguard Sergeant might be better so you have decrease def on CB? 

You could use Umbral on your arena team for her gamechanging AOE provoke, although of course you'd have to give up one of your two nukers. Would be useful to have as an alternative even if you don't put her on your main team, anyway. 

Next level 60s I would say, not necessarily in that order: Mausoleum Mage, Frozen Banshee, Apo, Umbral Enchantress if you want to start using her. Sandlashed Survivor, Rearguard Sergeant, Cardinal, Juliana could be worth 60 too, the rest not I would say. 

Ok ! I'll see to upgrade Frozen Banshee masteries, because she has no masteries at the moment.

Cata is maybe not the best but atm I have arournd 1 more M (on 11M) with cata in comparisaon to Zargala. And Zargala is full masteries when Cata. is half masteries. Rearguard might be better I think since she had survivability but is more tanky but she is not good stuff/masteries atm.

I could swap Kael for Umbral in Arena I think. Today I tried Cata. council insteal of kael and I think it's better to down a key champ in the other comp and Skull have one more AoE attack so it's good :p

Mhmmm a lot of choice ! :p I think Frozen Banshee and Umbral could be next. Dunno for the next one :p

What do you think about juliana for CB ? I notice she has Burn and poison which sounds good. Dunno if she can replace my poisoner or come in addition to one poisoner ?

Juliana only puts 2 x 5 percent poison for 3 turns out of every 5 turns. Though indeed she has a HP burn as well which does more damage than a poison, how much more depends on your CB level. 

Frozen Banshee has 2 x 5 percent poison for 2 turns on her A1, but the complication is that those only work if she has previously put poison sensitivity (which lasts for 2 turns and you can put it once every 3 turns when booked). On the bright side, the poison sensitivity makes her poisons do 25 percent more damage (as well as those of any other poisoner on the same team). 

In practice, if FB is fully booked, doesn't miss any poison sensitivity debuffs and has high enough speed (or gets extra A1s from ally attack/counterattack), she can keep 4 or even 6 poisons ticking on the CB on nearly every single turn he takes - and doing more damage per poison than Kael or Juliana. But if she does miss her poison sensitivity, she won't be putting any poisons until 3 turns later when you can try again. This is mainly a problem with off-affinity CBs (so force) where 30 percent of her hits will be weak and automatically fail the debuff, even with sky high accuracy. Juliana and Kael are sadly the same affinity and will also struggle against force - Occult Brawler, if you can get him, would be a good back-up poisoner for force affinity CB. 

Thank you for you answer ! I took the team to fully mastery, skills and level Frozen Banshee and indeed the damage output is there ! At the moment I don't have enough debuffer and so I use Kael and FB together, it's in this way that I get the most damage. And with that I can go for brutal CB in 2 keys.

But I have new questions because with sacred shard event, I got a lot of interesting epics and my first legendary !

At the moment I'm thinking of upgrading two teams. One for CB and one other for dragon 20 (I'm at 17). Here is my "new box):

So now, I'm lvl Cupidus which looks kinda good. But I don't know if I should build him for Arena, Spider or CB ? Where would he be the best ? And should I invest my Legendary book on him (I'm not sure it's is worth investing those on him) ?

For dragon I have no idea what's the best at the moment. I mostly have hard time to kill trash then the dragon.

For CB I have Frozen Banshee, Cupidus, Vrask/ Reliquary Tender or Apo as healing, High Katun or Apo for speed and then Mausoleam / Lightsworn / Sepulturer Sentinel/ infernal baroness. Rearguard sergeant for either ATK decrease and/or Def decrease.

I'm a bit lost with the choices I have and would need a bit of guidance :(

Thanks a lot guys ! :)

Mauseleom mage for CB. I just got him to work on alt and I can 4 key NM. Make him just faster than boss, 171 or 172 speed. Do 1st 2 rounds on manual and use his a1. Then he will block stun every time. He can be used in dungeons also. Will be big help everywhere. I use on dragon20 and golem 19/20 

For CB my team is kael (temporary) mage coffinsmasher brawler(u have banshee) zelotah 

Build cupidus for spider but will be useful in lots of areas

Mage

Coffinsmasher 

Cupidus 

Apothecary 

All should be 60

Thank you for you tips !

I'm not sure why Zelotah, he does no debuff (sleep is not usefull on CB right ?). Just profiding shield and 2turns continuous healing every 4 turns. Isn't it better to have Reliquary or apo as suppoort ?

If someone else has other advice I take it ! :D

And for CB, would you prioritize Stag knight (Just loot him) or Coffinsmasher  ?

You just got stag? He is top 5 epic imo

But coffinsmasher is better for atk down on CB

But stag you can use in EVERY team. Needs books!

I run him in reflex gear which I think is perfect for him