You have a lot of really nice champs in your roster, worth lvl 60.You have to do much more campaign 12-3 instead of dungeons for now. Lvl up your champs, lvl 50 champs don't shine in high level content.
Especially for CB, a lot of damage comes from Warmaster/Giantslayer masteries. Your champs have to be lvl 60 to unlock these masteries. Furthermore a lot of healing can be done with the named masteries and life leech sets or a leech debuff at the CB.
On the long hand, Frozen Banshee should replace Aothar in your team. They do basically the same (poison), but FB does it better.
But I think FB can wait a little bit, my next champ to max would probably be Aox. He does some poison, but his other skills are the key for your team. You really want decrease atk on the CB, he heals a bit and his passive (debuff extension) is great.
Later on Fenax and Mordecai are worth lvl 60 as well. Fenax is the Ice Golem killer. Indeed he kills not the Golem himself, but his sidekicks. Fenax A1 hits like a truck (damage multiplier 4.1 x atk, 1454 base atk and double hit if the target has any debuff [basically every time a double hit, your team should be able to put any debuff on somebody]). And his A1 has block revive, if he kills the Golem's minions, they stay dead. I recommend to forget about his debuffs, build him damage only and disable his A2 and A3 in the team setup.
Mordecai is the spider exterminator with his Hp-burn on all enemies. Great strategy vs. Spider in higher dungeon levels: Hp-burn on all Spiderlings, keep the turnmeter of the big Spider down (Armiger, Soulbond Bowyer for example) and wait.
