Instructions
Level your characters and learn quickenings from the License Board.
Enter into combat with those characters who have quickenings and let that character reach full mana. When the mana bar turns orange, select the Mist command and choose to use the quickening.
Look in the bottom right corner of the screen during the first quickening attack and you will see your other characters names turn white with a button icon next to it. This means they too have a quickening that can be chained to the character currently using one.
Press the button corresponding to the character that has a quickening available. If there is not one, press the R2 button to shuffle through your other characters to search for an available quickening.
Chain together multiple quickenings to create large combos that your enemy can not interrupt and possibly trigger a Concurrence, which is a powerful finishing attack based on the number and power of used quickenings.