Short clicks are the most efficient. click right on the edge of the ground you want to clear and it only costs 1 energy. You can easily cover 30 energy worth of distance in 10 if you just clear it 1 energy use at a time.
Level 12 glitched for me. I tried clicking the door, then i used two of my three free hints, and then i bought the solution.
Reloaded the game, click on the door, and it worked fine.
Protection Ignore is broken once you get a level 15 wep. I'm at 132 protection ignore, and i'll crit for 60,000 damage (i have huge crit multiplier too). When i remove my protection ignore piece, i only hit for 5,500ish.
If you did not get the "HARD" badge after beating the game, replay the levels with the "Crossed Swords" as an icon. Once all the icons have the "Gold" / "Silver" / "Bronze" medals as icons, you get the badge. I had to replay 2-3 levels.
 "Earn to Die 2012: Part 2"){kind=icon}
 "Diggy"){kind=icon}
 "Mystery IQ Test"){kind=icon}
 "Battle without End"){kind=icon}
 "King's Guard"){kind=icon}