These are the Soul Collectors spots. There are 6 spots to find.
Bottom Floor Spawn Room http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=972605261
Middle of Map where Speed is http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=972605297
Near Stamin Up http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=972605332
Near Jugg where Box spawns http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=972605370
In Front of Widows Wine Behind Power Room http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=972605413
At Pack a Punch in front of Mule Kick http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=972605453
Rewards can be (so far what I got)
Minigun
Weapons (NV4, UMP45, HBRa3 so far I got)
Free Perk (Only way to get Eletric Cherry for free without using gum)