After completing the questline and leveling all kingdoms to 10 is there any point in doing the callenges?
Mostly, no.
I think the only possible benefit is (I think) challenge matches are fixed, rather than being subject to shuffling like Explore matches. So sometimes if you are soul farming it’s faster and more predictable to do that in Challenge matches. (But you have a lower chance of arcane traitstones.)
If you’re interested in getting souls then yes. There’s a decent soul reward from each one. I did most of them early on, before i had a lot of good troops it was a bit easier getting souls that way than in explore. The rest i left til a few months ago when i was farming for dawnbringer, once i had completed all that i missed early on i farmed the easiest challenge on warlord IV and had my 1.3 million in a week. When i was really early on and mostly clueless i farmed the easiest challenge for treasure maps. I was in a pretty much dead guild then so that was a great source of resources for me. Whether or not you chose to do them depends on your priorities, deck, and how easy it is for you to get those resources otherwise.
I did the challenges of 4 kingdoms when i just started, as in low level and low cards , cuz that was easier then explore with the cards i had.
Now i have done the whole questline and got a fast team for exploring, gold. Souls team i am working on. PvP i got a fun team for now so that brings in most gold atm but was wondering if i missed out on something by ignoring the challenges.
And was wondering where i could get the dawnbringer but i understand now that i can make that in the forge