I love this game but it is dying for me, I will not spend money and this lvl/rank/energy/legendary wall is way too insane if you do not pay and it kills me to have spent this many hours, as much as any high tier console or pc game, and have VERY little to show for it growth wise, just repeats of artifacts and rares.... soooooo when I saw 75 energy as a reward for this quest it blew my mind!! Yeah after 2,000 energy just to get one done. Yeah, these artifact missions are a JOKE! That or you are LITERALLY hoping people spend real money on energy to use to finish these ABSURD rip off "Challenges" in which they lose REAL money and time. How is it a "challenge" if everyone has the same 1.5% chance to draw the same artifacts? Don't you mean a gamble or lottery where each 4 energy spent is worth 1 ticket?
This seems like you forcing your customers into such a hard spot that they will crack and spend some money at some point, like the Arena. Good luck getting to silver without spending money to get a legendary (I have 1 epic Not including the free, which do not help, and I have played for 3 weeks straight).. and then you gotta lvl them. All for the endgame of what? To be the top on a mobile game that'll be dead in a less than a year?
Who works for you that thought this would be a good challenge?? With your games absolutely shoddy roll system for any chance at a friggin legendary let alone an epic you would think someone would say "Hey, maybe we should ramp up the chances the more energy spent." 75 energy? A normal skill book? This is an absolute rip off and I refuse to do the challenges ever and because I have O.C.D. it means that I cannot finish this game.
Fix this or not there have been too many mistakes and too many people will be displeased no matter how this goes. You made a large mistake allowing this screw up to go so long and let so many people spend money they are now invested and will be screwed if you fix it for everyone and give them what, 1000 energy as a "my bad"? If you do not fix it people will continue to be furious and you will lose players.
Seriously, because of "Pay to win" you slammed yourself into a very hard spot with customers.
Fix it or not, this should be a huge lesson for you. And if someone DOES spend more money or more time like, I do not know, running the firekeep with 800 energy non stop should at least drop 1 of each different item not countless sets of Immunity!! And WHY SO MANY SHIELDS AND GLOVES?!?! Again, I seriously do not want to play anymore because of how long I have played and how VERY little I have to show for it.