This achievement is obtained in the Chalice of the Gods dungeon. You'll obtain it by falling from the room that's second up from the bottom in the third column on the map.
You'll fall from the right side of the room.
I suggest falling from the right side of the gap, but the left will also work if you push right immediately. You'll want to remain on the right side so you land on this ledge.
Now you'll want to drop from the ledge, then immediately face right and shoot the top button. The button is on the right wall, between the first two spikes. Shooting this button will extend a ledge at the bottom, which will prevent you from dropping on to the snake and dying (please note that this ledge is already extended in my screenshot). The achievement should unlock immediately after you shoot the button.