dang, you really hit the jackpot, didn't you?

the two i would focus on at the moment are dazdurk and tayrel. both of them are great in pretty much every area of the game and they bring a lot of really important abilities to your team like aoe def down and cleanse. i would book tayrel first until his a2 is maxed and then switch to dazdurk (and later go back and finish booking tayrel).

as for the others, high khatun is decent but can do her job just as easily at rank 5 for now. she'll be worth ranking up eventually if you don't get a better speed lead, but booking her would be a waste. fahrakin is good, but he shouldn't be a priority at the moment since an ally attack champ is useless if you don't have strong allies. he will help a lot in clan boss like you thought, so definitely use him there once he's levelled. zargala i don't have a ton of experience with personally so you may want a second opinion on her, but she's also definitely worth raising. in comparison to royal guard, she's better at dealing with waves, whereas royal hits much harder on bosses.

your arena team sounds pretty good, save that royal guard probably isn't the best option for damage. since his a2 scales off enemy max hp, he's a lot more effective against high level bosses, but less so in arena where opponents will have much lower hp. either zargala or aleksandr would be more effective.

I'm keen to get information from you around your current builds for Clan Boss and Dragon, as well as the level, as I think these are the other areas (apart from Arena) that you should be focusing on right now.

You made a note about replacing Kael with Fahrakin, but I wouldn't.  Kael brings so much damage with his poisons that he should remain a key player in your CB team for quite a while.  For CB I would probably run something like

• Kael (damage and poisons)
• Runekeeper Dazdruk - Healing and increased attack
• Tayrel  - Decrease defense and decrease attack, turn off his A3
• HK - turn meter boost and increase speed, keep at level 50.  Should be the lead
• Royal Guard - Damage, already level 60 and should have warmaster

I also agree with Carpe_Piscis above that Royal Guard isn't the best source of damage in Arena.  The team you have is solid, assuming you have the speed tune right (HK into Runekeepr into Tayrel into nuke), but you need a better nuker.  Kael will do the trick quite well, and since he can also help with CB then personally I think he is worth taking to level 6.

Cheers @Carpe_Piscis  and RoseRoyal.  

Thanks for your comments.  I don't really have set builds for either Clan boss or Dragon yet.  I was looking at the champs i've pullled and feeling a bit overwhelmed.  Seems I should focus on getting Kael, Tayrel and Dazdruk to 60.  Book out Tayrel first then Dazdruk.  Bring Kael into arena once hes maxed out.  Perhaps later down the track bring in zargala to arena (low priority though).

What level of CB are you running at the moment?  It sounds like you might not have started to look at this content, and if not then just use the team I mentioned above as it is and see how much damage you can get.  The goal is to get the last chest with 3 keys of damage.  The above team I mentioned should be able to do Normal if not Hard and get the highest chest, assuming the champions have decent gear.  If you find that they are having difficulties then maybe post your gear and we can help on that front too.

The thing about CB and Dragon is that in a lot of ways they are actually the same in terms of team structure, especially in the early to mid game.  This means that once you get a good team for one, you can use most, if not all, of it for the other.  The other dungeons (Spider, Fire Knight and Ice Golem) usually have some extra mechanics that you need to consider and if I were you I'd park those for now and focus just on CB and Dragon to get comfortable.

One of the biggest challenges isn't just having the champions, but also the gear to make them useful.  This is why Dragon is a good dungeon to focus on because the lifesteal, accuracy and speed sets that drop there will be useful for all of your champions at this stage of the game.  Ideally you want to start to get 5 star gear consistently from here to start to have some artifacts to play around with

Edit: Personally, I'd focus on getting Kael to 6 stars.  He will essentially have a role in CB, Dragon, Arena and as your campaign farmer.  The fact that he is a rare is good because he is easy to book, which you have done already.

overall i second everything here, but i'm going to have to disagree on one major point; using royal in your cb team. 

op, don't use royal for clan boss any longer than you have to and absolutely don't take warmaster as his t6 mastery. it's true that warmaster (or giant slayer) is absolutely essential for cb in order to maximize damage, but royal guard will get significantly more damage everywhere else with either helmsmasher or flawless execution. his kit also isn't particularly good for cb in the first place, so he should be dropped from there as soon as you're able