Issue 1: probably… there is a schedule to getting the stat bonuses… sorry, can’t find at your level but did find this showing the pattern later…
Tacet:
Hero leveling stats are fixed. There is currently nowhere that a full list exists.
I do know what all of them are at 50+, but not previous to that:
Magic: 50, 100, 500
Life: 60, 90 200, 750
Armor: 70, 150, 400
Attack: 80, 300, 1000
Basically it really slows down as you level up…
Issue 2: sorry, bad luck sometimes happens, and we all have a memory biased to obsessing over it… been some time since I did those challenges (over a year, probably!) but I don’t recall any being unbeatable… maybe come back when you are stronger…