Sepulcher Sentinel and Fahrakin the Fat both stand out to me. They're both renowned as great Clan Boss champions and certainly worth building.

It looks like Versulf the Grim also has an A3 that has ally protection and increase defense, though I'm not entirely sure if he's a quality champion that is worth booking and completing. 

For reference, the things you need to survive in a killable (traditional) clan boss team are:

• Decrease Attack 
• Increase Defense
• Ally Protection

Sepulcher gives you decrease attack and increase defense, as well as block debuffs (that Marked is giving - but SS is better). 

Versulf could give you the ally protection, but again I'm unsure of his value. 

Fahrakin gives you Decrease Def A1, his HP burn and poison A2 and a great ally attack A3. 

Geo is geo.

Ronda is solid.

First and foremost, you need to realise that "healing" in CB doesn't exist in the traditional fashion. There are very few workable teams that involve having someone do direct healing. The vast majority of CB teams get around that in two ways - either with block damage or unkillable, so that you don't need healing at all, or with leech and warmaster/giantslayer.

So, with that in mind, you're fortunate in that you do actually have a leech champ - Versulf. His A2 has two chances to land leech, so against non-green affinity, you're pretty much guaranteed to keep it active. Green is a bit sketchier, but you should still be okay. And his A3 also provides you some much-needed protection

Geomancer is great for DPS, so you should also keep him on your team. 

For the remaining three slots, you need at very least two things - ATK down, and block/cleanse debuffs. Again, fortunately, you've got one of the all-stars for this - Sepulcher Sentinel, who does both of those two.

To round out the team, I'd go with Fahrakin the Fat, for ally attack and debuffs, and Ronda for DPS. You'll want one of those five to be running a Toxic set, as none of your champs are poisoners.

You can use this tune: https://deadwoodjedi.com/speed-tunes/single-43-advanced/

Specifically, this one: https://deadwoodjedi.info/cb/55f338ec8f3b8d14a59e838a4cb319faf2481e4c

In terms of who takes whose place, Versulf will replace Skullcrusher, Fatman will replace Rhazin, and Ronda will replace Frozen Banshee.

Damnit. One minute too slow :p same team comps too!

lmao. The only thing I wasn't sure on is Versulf - I don't have him and I haven't seen too many people use him in CB. I did just check out a DWJ video on him in CB though - seemed solid enough

I used him on my CB team for a very long time. He works very well.

I think both of you overlooked that Canoness actually does provide leech, increase def and ally protection. She does basically the same Versulf would do. Why build a new legendary champ, that would need the rarest ressource in the game (legendary books) to become a help, if an epic, that allready is leveled to 60, can do the job?

/edit:

To be honest, this champ (Canoness) is actually good for CB. I ask myself why I never built her, I have several copies on my account. Increase def and ally protection for 2 turns - on a (booked) 2 turn cooldown, wich means it can stay active for the whole fight from her alone.

canoness' a3 is single target, not aoe.

Ok, I guess that is the reason why I never built her. 

Just forget what I wrote. 🙈🙉🙊

I'm getting old and need some younger persons with good sight to read for me. 😉 Thankfully I could read well ages ago, when I started Raid, so I did not build this champ for CB when I was younger. *cough*