Feral Fury (UP)

What Syringe Rooms do- all your stats go up but you lose one square of health.

The Syringe Rooms are the green outlined rooms that will appear on your mini-map (top right of screen).
You just have to explore a bit to find them, once inside go to the center of the room and stand in the middle circle, to get the syringe.
After a couple playthroughs you should find enough of them in no time if you explore enough to get this achievement.