User blog comment:Zombie jotuc/HELP i cant kill bunbun!/@comment-24659969-20170217011515/@comment-24659969-20170217063741

Well, battlecats is a grinding game in the first place. If you think getting all normat cats to lv 20+0 is hard, then levelling up ubers are harder.

Most uber rare units XP requirement for level up is about 5 to 10 times of normal cats.