Command Meld

In Kingdom Hearts Birth by Sleep, Item Synthesis does not occur. Intead, a new method known as Command Charge is used. In Command Charge, the player can mix two Commands to form one new Command. Like in Item synthesis, the player can also add materials, namely crystals, to add effects. By adding a certain crystal such as the Rolling Crystal with a certain Command, the resulting Command will possess a Support Ability, such as halving its cool-down time or increasing damage.

Examples
An example of Command Charge's effects would be the mixing of Fire Blitz and Aero to get Aerial Slam. The addition of a Moisture Crystal to Fire Blitz and Aero would instead result in an HP UP.