Yeah, I think there's a lot you could change... also, why do you use Spirithost at all anymore if you have Gorgorab AND Battlesage, both of which do basically everything SH does, but better? Some other amazing champs in the vault too, including Umbral Enchantress and Royal Guard.
For CB, you generally want all of the following, with as close to perfect 100 percent uptime as possible:
- poison
- decrease attack
- decrease defense
- increase defense on your team and/or ally protection
- healing/revives
- if you have the champs for them, counter-attack and/or unkillable setups; if not, being able to speed up your team can help too
- also nice to have but less essential are weaken, HP burn, increase attack on your team, debuff extenders
I don't immediately see a reliable decrease attack debuffer on your roster, that's a problem. For decrease defense, you could probaby use Royal Guard, who you should make 6* for dungeons anyway. For poison, FB is better than Kael (the problem is his weak poisons which just get in the way, remember there's a maximum of 10 debuffs at a time on the CB), although since Kael is level 60 and perhaps has warmaster already, don't switch just yet. Not sure if you could use both - you could try, but you may have the problem of the 10 debuffs max and if Kael's weak poisons prevent you from placing strong poisons or important debuffs like decrease defense, that will hurt you. Blind Seer is excellent for shielding, healing, revives, definitely keep her - and put her in lead! Her defense aura is great, more important on CB than the speed aura you could get from Battlesage. Flesh Tearer... debuff extension plus some healing, I guess worth keeping if you have a spot free anyway.
So in short, you should have Blind Seer lead, Royal Guard or some other decrease def, FB eventually but maybe Kael for now, Flesh Tearer and then either FB/Kael if it works to have both, or Apo, or maybe Drexthar but I don't think he'd be worth it for the HP burn alone. But you really need a decrease attack champion as well.