What stinks is one deck can win you every challenge well at least my dark deck did
And for the 1 heath one its half luck just for me i got 2 of my weakest unit and least power consuming and put them out, then i attacked with one and i used the other for blocking i repeated a process like this until i have 3 power then i used Drain Life
so easy
Hint: use Memory Erase ( black card) when you have used up all you cards so dont draw and just increase power to 6 then use it when u have no cards and the computer becomes predictable and easy ( i used this on last challenge )