That looks like Dracomorph? If so, he should 100% be on your CB team. Frozen Banshee pairs well with him for the poison sensitivity debuff. Siphi should be good as support, with enough speed gear you should be able to keep her block debuffs up for the A3 stun. Skullcrusher is always useful for CB. For your fifth, something with ATK down would fit well. I'm not very good at recognizing champs from their pictures, but I'm sure you have at least one in there.

lol, yes he has tayrel... 

you just need to 6star your top champs. tayrel siphi skull

so many good champs, I don't even know where to start. wow

I do have all 3 of them in my CB line up, I was trying to push arena to improve my great hall but it seems I can't go past low silver. I currently use high khatun, draco elhain and kael even tho my high khatun runs at 235 speed I do not have good spead gear on the others without losing burst power so most of the times I either lose the speed battle or somebody jumps in between and screw me over. 

Since Great Hall is such a massive place to gain accuracy etc I wouldn't have minded investing more into arena to get a good level of Great Hall and then jump back into PVE content.

Too many things to do I guess

replace elhain or kael with umbrall in arena.   You have 3 attackers (Bellower, Kael, Elhain) -- probably all poorly geared.  Pick one to be strongest nuker.

CB should be SC (book CD), Tayrel (needs books), Draco (booked I assume?), Narma (will be just fine without books), Doompriest (dont bother booking)/Siphi (guessing u r out of lego books) 

Either Umbral indeed or replace with Siphi instead - she can give a secondary speed/TM boost while also blocking debuffs. 

Plus, in some arena battles it could be good to swap Siphi into the lead slot and go resist instead of speed. 

Draco only got 2 books in since I got it far after Siphi, although Siphi is fully booked. I'll have a look around to regear everyone but if i go for pure speed or a decent amount at least I lose tons of power. Haven't tried Bellower yet into the arena but he isn't booked at all.