just got the hard badge. the way that i did it was not worry about upgrading any skills just do the missions to get your multiplier up when you get to around 30 for a max multiplier then buy a multiplier booster when you are ready to go for the hard badge. i did this badge with only level 1 on each one of my scroll skills just takes some time =)
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 "DJManiax"){kind=icon}
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 "Storm the House 3"){kind=icon}