On master hero, these missions do require alot of skill, firstly consider an incredibly high attack hero, around 250-300, as you need to kill enemies fast, remember you can go back to the base to heal yourself, kill all flying enemies as they will just target your base, use summons such as rhino to drive them back, as you can see the enemies on the map a timed teleport can get you passed the lines take out a tower with ice burst or death touch then port back to behind your minions. Hope this helps.