How do I get to the new "Cow Level" in Reaper of Souls?
Solution 1:
The cow level is a random rift level. Similar to "development hell" crypt in act 1. You have a random chance of having a rift level spawn only cows, killer bears, or have 25 treasure goblins all huddled together. There are many different rifts that offer a lot of different enemies. And it's all random.