Small and AI-helped drop. Revolves around Dens (which are dungeons)
Quests
Defeat 100 skeleton mobs.
New hostile mobs
Skeletons, zombies, variants
Bosses
New guardian of the new dimension, keys, and biomes
Boss Music
Music disc versions too
Items
+35 new armor sets +35 new weapons
Dimensions
Find the ten keys from a new biome. Unlock the portal. Step inside.