How To Go Beneath

The sacrifice needed to go Beneath is great. First, hold a Scythe. Find a Pig, Goat, or Sheep. Then, obtain seven offerings. Valid offerings are skulls, anvils, placed gold, pig iron, or black steel ingots, and gold or black steel plated blocks.

Kill the animal within a 5 block radius of the offerings. A portal will be created, but be warned! The Beneath will temporarily invade your world, wreaking havoc and causing confusion.