I THINK IT WOULD BE BETTER TO MAKE THE BONUS 4 
CHALLENGE AN ESSENTIAL CHARACTER CHALLENGE WITH A TEAM UP, AGAINST THE LEGENDARY CHARACTER AND A COUPLE MINIONS INSTEAD OF THE ONE ON ONE CHALLENGE, I HAVEN’T BEEN ABLE TO PARTICIPATE IN ONE YET BECAUSE MY FOUR STAR CHARACTERS AREN’T LEVELED UP ENOUGH
You’ll get there soon enough.