Upgrading artifacts to lvl 16 is impossible. I had more than 2Ml wasted all of them and didn't reach lvl 16 once!!! Why make things impossible?! I get making things tough is part of the game. but why impossible?! wht? how am I supposed to upgrade the artifacts if the game doesn't allow it?! 

Please.. I have this problem of finishing the task.. Its about the artifact,,, or should rather say putting a attack equipment to a attack champion (or a hero)...

This brings alot of stress.. Ive done it once but when i do the same thing to the other attack type heroe's its not working,, i have waisted alot of my silver earnings by removing, replacing item all over and over again and again..  

It is really BS. Thinking that the instructions is very clear to read and understand but not working when you follow it,, ive have played this game 2 years ago and stop because of this matter, and came back to try playing the game again and its really dissapointing to say that untill now im still facing the same problem 2 years ago.. 

I am just an ordinary gamer that needs to follow all the task and instructions just to make my champions or heroes stronger,, following and finishing is the only way i can do to make it happen because i dont enough or an extra money to use or spend on this type of game.. So please.. I know your doing the best that you can to fix this  problem, but please show us some improvements on what you provoke.. Thank you for reading this matter.. 

I have this same problem... 

I've spent (aka wasted) around 500 energy trying to get a 3* glove in the sewers on normal.... the reward for completing this challenge is 50 energy........................................ What  the  heck  is  going  on?😠😣😣😫😫😠😠 I never thought this game would cause me to feel rage, but this is absolutely infuriating.... I still  don't  have  the  gloves!!!   Now I'm at around 600 energy wasted..... Broken???

Edited

Not broken, just an annoying mission that requires pure dumb luck. I hope you're at least farming XP while you're doing this? 

Also, I don't remember all the exact missions, but some of them will work on any difficulty - if it doesn't explicitly say that it must be on normal, you can do it on a harder difficulty so you can farm more XP. 

These are challenges 6 which require them to be done on normal stages. Although now 2 stars is sufficient, I still haven't got even the akt% gauntlets after 100 attempts.

How do clear Challenges 6.1? Tried putting my Level 5 Champion attack with their primary stat atk(%)  on the boots, chestplate and guantlet.  It also resulted in winning a 3* gaunlet, however it still did result into a completed challenge.  How so? 

me too.  I can't seem to get the instruction?

And then an Attack% after that. u__u¿

2 years later - the challenge now says a "2* or better" drop, but a 2* drop, (using all 4 Attack characters), does not complete challenge 6.1 - it did not complete until a 3* dropped.

Nice patch, guys!  Changed the text but not the mechanics?!