Minecraft's new update introduces an all new enemy, the Wither, a combination of Skeleton and Blaze.
Slimes now spawn in swamps as well as huts containing witches who attack with splash potions. Zombies are now able to infect villagers, though infected villagers can be cured. Enemy mobs can now pick up armour and weapons and use them. Bats spawn in dark caves. Anvils can be built to repair damaged weapons and tools.