Custom adventure maps just became a hell of alot easier!
Short list of included features...
A 'Quick Build' command based world editor to make creating structures simple
Edit player skulls to have custom heads
Edit books title and author to how ever you please and revert a written book into a editable one
Edit the settings of spawners to have custom player detection, max delay, min delay etc
Create custom villager shops and more
Apply potion effects onto item potions and customize their colour, type and type/amount of effects the potion has
Apply enchantments to any item
Fill dispensers with a click of a button
Edit an item name and lore choosing colour and text
All these features are only available when you have forge and the mod installed. This mod is meant for the creation of custom maps and then when the map you create is opened in a minecraft environment that is without the mod, all the edits you made to the world will still exist.