This tutorial was a little bit late, but I made it anyways due to the valuable information that you all could enjoy.

First, you need to be in creative mode and build a structure similar to the one above.

Then, you need to spawn wolves into it, as shown in this picture:


Now that you've spawned about a billion wolves, it should look like this:



Awesome! You made yourself a circle composed of a billion compressed wolves!

Then, there's only two things left to do:

-Hit one of them to get a billion new enemies
-Push the lever.

Now they're all attacking you. Hope you enjoyed!