This achievement must be done in the new map "shadows of evil" It requires the use of a brand new perk to zombies "widow's wine".
To find this perk, load up a game on shadow's of evil (solo or multiplayer, doesn't matter) and begin. You will need to open at least 2 doors and buy the perk, totalling 5500 total points. It will be made much easier to get these points by purchasing a weapon, I reccomend the vesper, but really any wall/ box weapon will be fine. When you spawn in open the only door you can see (cost 500 points, which you start with) and then begin killing zombies (6-8 shots to the legs with the bloodhound followed by a knife will maximize points on round 1) You now need to earn 1000 points.
Once you have this amount open the door with the words "footlight district" (although any of the three doors will work, footlight is just easiest in my opinion) above it for the 1000 points. At this point, it is reccomended you save a zombie on the current round. Now it is time to open the rift.
As soon as you enter the footlight district you will round a corner and see a glowing purple orb on a pedestal go up this and hold
this will turn you into a squid monster, which allows you to move much faster and is necessary for unlocking many parts of the map, you have a limited amount of time, so you must act reletively fast. In this "beast mode" you must continue through footlight district a few meters, keeping left, until you see a small alleyway. Head into this alleyway and you will notice a large door to your right that has been bolted shut. Open this door by slapping it with a melee atttack using
. Now you can return to human by either waiting a few seconds for your beast mode to wear off, or simply holding
. Head back over to this door and enter it, you will see a yellow beam of light, hold
on it to open up the rift. Enter the rift and head directly forward, you will see the perk "widow's wine" on the opposite side of the area. If you are playing solo you can go into beast mode a second time the same round, if you're in multiplayer a different player must go into beast mode (there is a pedestal in the rift area). Whoever is in beast mode now must walk up to the perk and shock using
a little electric box to the right of the perk machine, powering it up.
Now it is just a matter of getting 4000 points. The vesper makes for an excellent point weapon and can be purchased in footlight if you head back through the portal.
Once you get 4000 points, buy widow's wine.
Widow's wine works every time you get hit by a zombie, it releases a shockwave that ensnares all zombies around you in spider webs, preventing them from moving for a few seconds. As well, it changes your frag grenades into special sticky grenades which explode and have the same spider web affect on zombies (thrown with
). To unlock this achievement, you must only ensnare zombies using the grenades, not the shockwave.
Thanks to PatchyAmac for mentioning that it does not matter how the zombies are ensnared, it can be by grenades or by shockwave released when hit. I recommend getting a sizable group of zombies together and ensnaring them with a single grenade. When they are ensnared begin shooting them before they escape.
You must kill 10 zombies like this and the achievement is yours.
If you run out of grenades, every few zombies will drop these glowing spider symbols, which when picked up reward you with more grenades.