mrbellek20,439 Locked 22 Feb 2016 26 Feb 2016
Getting to level 100 will take you a few resets, and it's nearly impossible to get there on your first try (i.e. no resets and no idols). Resetting will give you idols, each of which will give you a 3% damage boost. I was able to make level 100 on my 4th try (3 resets) with about 30 idols.
Make sure to keep an eye on the damage your crusaders do (shown in their box in the bottom area) and level them up accordingly, instead of just blindly leveling Nate Dragon. Crusaders get a 4x damage boost when they hit level 200, and a 2x boost every 25 levels after that.
The achievement will unlock when you reset the world after beating level 100 or higher.