Bukkit

2.0:
To avoid errors with the setMaxHealth, you have to have at least CB 1.4.6-R0.3

• Add support for Baby Zombies, (Baby) Villager Zombies and Wither Skeletons.
• Use the setMaxHealth() method and update actual LivingEntity health
• Add support for boss health regeneration
• Automatic updater (using dev.bukkit.org), use /lab update install to install the latest version, if necessary
• Added option (in config.yml) to disable update checking on startup, you can still check for updates using /lab update check
• Configure immunities per boss
• Configure which MagicSpells spells affect bosses
• Automatic config updater
• Fixed occasional NullpointerException in bomb ability, the Bomb ability now tries to find a valid block close to the player. (thanks to bm01)
• Multiple bosses of the same EntityType can now spawn in a world
• Added per boss immunities
• Added the option to use the boss stats as absolute values instead of multipliers
• Added an ability assignation chance (thanks to bm01)
• Added a radius for ability executing
• Added possibility to grant extra mcMMO xp for hitting bosses
• Added proper Wither support
• Added teleport ability (thanks to bm01)
• Added option to make PigZombie bosses angry
• Added function to set absolute health for bosses
• Added option to check the size of Slime/MagmaCube bosses
• Removed deprecated API, as already advised in the last version, use the new one that is already present in v1.7.0.

1.7.0:
To use the custom armour, you have to have at least CB 1.4.5-R1.0

• Enable/disable MagicSpells spells on bosses
• (Configurable) armour support for bosses including enchantments (screenshot)
• Added LightningAura ability. A boss strikes everyone within a certain radius with lightning
• Fixed ignore command

1.6.6:

• Added API

1.6.5:

• Added {BOSSNAME} option to messages in the config to get the bossname properly. (BossName#1 would be displayed as 'Boss Name' to a user)
• Added 'Bomb' ability
• Changed 'Slow' ability into a generic 'Potion' ability which can even target the boss itself
• Added customisable message if a boss uses an ability (configurable for each ability)
• Readded the max spawn level/height option
• Added a cooldown for all abilities
• Made the Lab Viewer message customisable
• Made the message if a boss has a negative health customisable
• Changed the probability option from the chance a mob gets an ability to the chance a boss successfully uses an ability. (Will be readded but probably with a different name)
• Changed deprecated spawnCreature method to spawnEntity
• Fixed Utility.isNear method (which checks if two locations are near each other) to support multiple worlds
• Tiny slimes that split from a medium slime won't become a boss.

1.6.0 (By bm01):

• Added abilities
• Rewrote the boss managing system
• Rewrote config processing