1. You really should have made a 6* champ, your overall progression would be better. But as you can't change the past, you can still go on the right way: The first and most important step to further progression is, to build a dedicated campaign farmer. A champ that, lvl 60 and with good enough artifacts equipped, can do campaigne stage 12-3 (most silver, as shields can be sold for the best price, I prefer 12-3 over 12-6) or 12-6 (best xp) alone, paired with 3 useless champs that are just leveled up to serve as food for increasing your real champs. 

The campaign farmer will help you getting your other champs lvl 60 faster.

A lot of champs can do that, probably Kael is the most usefull of them for you, as he can fight in your Clanboss Team with his poison as well. Bellower could do the job as well and serve in other locations. Bellower is very good in a stun set.

2. Arena: High Khatun, use your fastest speed gear. Spirithost, make her fast, she needs to go as second and use her atk buff. Uugo has to go third and use her decrease def debuff on the enemy team. Use your epic books for her, she is one of your best champs and will serve in a lot of teams. Kael for big damage.

3. Clanboss: Kael (poison, will be removed later for a better poisoner, but you want him to be lvl 60 anyway, see above). Vrask (healer for your team). Coffin Smasher (atk debuff and hp burn, use accuracy or perception gear to make his debuffs land). Mausoleum Mage (def buff, block debuffs [stun]). Uugo (def debuff, leech).

4. Champs not mentioned above, that are great for dungeons: Royal Guard (his attack scales with enemie hp, great for late dungeon stages, where the opponents have tons of hp), Tuhak and Soulbond Bowyer (the Dragon is immune to turnmeter reducing effects, but at Spider and Fireknight you will love them).

Thank you Skadi. I will work on getting Kael to lvl 60 and go from there!  

Skadi, I received Dark Athel tonight. Would you upgrade her to lvl 60 or should I stick with upgrading Kael to 60. What do you think?

stick to Kael, Dark Athel isnt good

wait for Royal Guard until you hit lvl 16+ dungeons, he is great later but early on not that good

Uugo, Bellower are great Champs well worth taking to 60

Mausoleum Mage is also good but I'd keep him at 50 for now, but is also 60 worthy

still focus on Kael first

Thank you Lichwyrm.   Appreciate the help.