This mod does one thing and one thing only: Add the new Lava Chicken disc to older versions. You can get it in the same way, by killing a Chicken Jockey. Make sure to kill the zombie first, or it won't drop.
La-la-la-lava, ch-ch-ch-chicken
Steve's Lava Chicken, yeah, it's tasty as hell,
Ooh, mamacita, now you're ringin' the bell,
Crispy and juicy, now you're havin' a snack,
Ooh, super spicy, it's a lava attack!