Goatz - After outbreak
For this achievement you must collect the 3 barrels, place them into the side of the RV, go inside the RV, lick the crystal, find zombies, freeze them (just by going near them), then hit them with
Some video guides show that you must go back to the RV each time your crystal breath runs out, but that is not necessary. You will notice small patches of crystal that you can lick spread out in the map.
Remember, you can turn humans into zombies with
Do this to 30 zombies (human zombies & animal zombies) and the achievement is yours.
Credit to 'Press A 2 Join' for the video guide showing the location of the barrels and RV: