Semi Hard only because there are a lot of steps, but once memorized it's fairly easy to pull off.
After initial overlord the others should be spread out just beyond where our creep spread goes to extend vision.
This build is meant to counter the standord Marine/Medivac/Mine attack that typically ramps up at 12:00. The major initial attack will happen at roughly 11:00 when production is just finishing up for the terrain and upgrades haven't quite finished.
You should have two or three overseers with the army. As well as sending in a few sacrificial lings to try to set off any close mines. Your worst nightmare is rolling in with a pack of banelings only to lose them all in one mine shot.
When starting the two macro hatches you should be at 16ish drones on all three bases and 12 on gas.
For a more detailed look at the build checkout Day9's Daily #613
Submitted by: TnekKralc