It's all about the buffs and debuffs with the clan boss. Basically you want to have the following as pretty much essential components of a CB team:

+Spd buff (gets you more turns to damage him)

-Atk debuff (Allows you to survive more turns at the end to damage him)

Healing of some sort (Keeps you alive to damage him, could be a healer, could be lifesteal gear or a combination)

Poison and/or HP burn debuffs (damage for these is based on max HP, though capped on the clan boss to keep them from becoming overpowered, they will hit hard).

Then you have the very desirable:

- def debuff (lets you hit the CB harder)

Weakness debuff (lets you hit the CB harder)

+Atk buff (Lets you hit harder)

+def buff (lets you live longer and your def champs hit harder)

+crit rate buff (Lets you hit harder)

+counter (lets you hit more frequently, really becomes essential later on when you're looking to improve on damage and have no more room to do so with gear and masteries)

+Block damage/Unkillable/Ally protect (all provide some measure of extra survivability to give you more turns at the end)

Then the also useful:

Block debuffs (To deal with the stuns and poisons)

Remove debuffs (To deal with the stuns and poisons)

Remove buffs (To deal with the +atk buff he gets if he's below 50%)

Also, look into the Warmaster and Giant Slayer tier 6 masteries - it's a mission to get to them, but they are also damage based on target max HP. Any champion with an attack based on enemy max HP such as coldheart or husk can also do good damage with those abilities, but they have cooldowns, unlike the damage over time ticks and Warmaster/Giant Slayer procs.

So based on that, Apothecary will give you a heal and spd buff. Warmother will give you a -atk debuff, plus some damage with her bombs). Kael and Ultimate Galek give you Poison and HP burn respectively. For a fifth choice, Frostbringer wouldn't be a bad choice, as she'll reliably provide Ultimate Galek with the Atk up buff he needs, keep the spd buff up if Apoth's falls off, and (somewhat less reliably) provide a def down debuff on the CB.

That's just a suggestion, you can mix and match until you find what works best for you. Focus on what each champion brings to the table in terms of the teams overall damage though, don't get hung up on individual ratings. I've seen ratings for champs on sites that make absolutely no sense when you apply synergies that are ignored in individual ratings.

Hope that information is useful for you.

Thanks, it is helpful. Probably in the short run I'll try to incorporate Apothecary & possibly Warmother into my team, and work on Ultimate Galek. The question then becomes who to 6 star next - probably one of those three.

Warmother provides me with maybe the biggest dilemma. She is my only legendary, and I've held off on booking her, waiting on a better legendary. But with two different people advising me to use her in my CB team, I'm thinking that maybe those 8 legendary books might need to be used on her. 

High Khatun only brings the speed aura and speed buff to the table. Her A1 debuff and A3 turn meter reduction simply do nothing to the clan boss because he's immune to it. That said, I use her for the very reasons you said, but I do have plans to replace her once I have a replacement trained and geared up for her. Speed is almost always useful, so High Khatun will never be useless. She's just not as good as a lot of others.

Regarding the lego books - they are not easy to come by, particularly when you're new to the game. I would hold off on using them on War Mother. Not all champions are equal as it goes with books, and War Mother (particularly as it relates to the clan boss) is one that benefits less than others from books. Her attack down debuff is on her A1, and has no increased chance from books. Compare that to Bad-El Kazar's Malice ability, which when booked becomes a 3 turn cooldown from 5 turns - a much better use of books. Books are most useful on cooldown reductions and debuff chances. Typically I find they are of maximum benefit on support champions.

As for who to 6 star, Apothecary is very useful pretty much everywhere (maybe less so on the spider boss). He's a great choice to 6 star. Warmother is also a solid lego, another good choice. Ultimate Galek is probably a bit less universally suited to different locations.

you will never regret maxing apo (I went with gs + support tree for chance at extended buff turns - landing 3 turns speedup makes it uptime 100% when fully booked ...)

I use my apo everywhere besides spider (dragon 20, IG 20, FK 17, arena - G4, NM cb ...)

6*, 6 ascend (gets more base speed on last ascention), fully booked, 2x speed + immortal sets (speed + def focused)

You will have plenty of rare books from hard / nm cb. I have like 50 laying around right now and no real need to use them anywhere - waiting for ch to max right away ...

Yeah, I agree with KSTHECR0W here. Apoth is so universally useful, he should be a priority for booking.

High Khatun and Seeker definitely need books if you're going to use them. Thing to consider there is - you'd typically use one or the other. Whoever you book of the two needs books on their spd buff/turn meter increase. You want that firing as often as possible. Seeker is better suited to teams that try to finish the battle in one turn, while HK is better suited to longer matches.

Thanks guys, helpful advice even for the short run, hopefully long run also.

-swapping in Apothecary and Warmother for Seeker and Coldheart has helped a bit in the short run, now doing 3.5 to 4.0 million on hard, not great but an improvement. 

-Apothecary in particular is really starting to shine, and likely will be my next 6 star.

-Warmother OTOH, while an improvement, just doesn't shine. I'd really love to be able to swap her out, but don't have any strong candidates to replace her (but see below).

-Getting Ultimate Galek to the point where he is usable is proving a challenge. The issue is that regular Galek, despite being much less well suited for CB, simply does far more damage as a result of being 6 star and otherwise stronger,

-While I understand the importance of getting the right buffs & debuffs, at the end of the day you still need heavy hitters to take advantage of the buffs and debuffs. Most of my damage is being done by Kael, with Galek a very distant second. I'd like to find a good hero to fill that role, but I'm not sure who that would be. I'm thinking of trying Zargala for Warmother. No Decrease attack debuff, but she does have decrease defense and weaken (do they work on CB?) & does a lot more damage that Warmother (& she's 6 stars rather than 5). Another option is swapping Coldheart back in, though I think I would need to use gems to max out her masteries & probably 6 star her for her to really shine, and of course she doesn't help me with buffs/debuffs.

-unless I pull a better hero, with my current heroes it's just going to be a long slow slog to the point where I can do significantly more damage in CB.

-While I understand the importance of getting the right buffs & debuffs, at the end of the day you still need heavy hitters to take advantage of the buffs and debuffs. Most of my damage is being done by Kael, with Galek a very distant second. I'd like to find a good hero to fill that role, but I'm not sure who that would be. I'm thinking of trying Zargala for Warmother. No Decrease attack debuff, but she does have decrease defense and weaken (do they work on CB?) & does a lot more damage that Warmother (& she's 6 stars rather than 5). Another option is swapping Coldheart back in, though I think I would need to use gems to max out her masteries & probably 6 star her for her to really shine, and of course she doesn't help me with buffs/debuffs.

-unless I pull a better hero, with my current heroes it's just going to be a long slow slog to the point where I can do significantly more damage in CB.

- -atk gives you few more turns to deal damage while cb would kill you on the spot

- GS/WM, when proc deal 38-60k dmg depending if cb have -def and weaken or either of them

- apo with 3 attack a1 procs GS on average a bit less than 1 extra dmg each turn (up to all 3 hits in single turn, that is up to 150k dmg on top of standard in single move ...)

I would estimate full WM/GS team to deal around 30% more dmg when compared to same team without masteries ...

- less impact on slower teams, big impact on fast or counter attack teams ...

my tayrel with 3,5k def and 94% crit dmg does around 2x 31k crits on a1 to NM cb with -def ... and extra 50k on top of that from WM every now and then ...

my apo ends with 1,5M dmg to NM cb with most of it going from GS (800k-1M ...)

Not having ca champion at all I resort to speed for damage.

- Tayrel lead with LS set (176 speed)

- BEK maxed with reflex set (197 speed) - WM + extend buffs / debuffs from support tree (3 turn poison and 3 turn heal by chance)

- astralith in avenging set (used in arena as well) - 186 speed and 95% crit rate (spam a1 for team TM gain if playing manual)

- Occult Brawler - 180 speed

- apo - 215 speed (rarely need to heal anyone as BEK does it rather well - speed buff and a1 only till really last turns ...)

auto NM does around 15-18M per key in about 5-6min