It allows a user to select a tag from a menu of all of the tags and then have a deck and subdecks made out of the selected tag and its subtags, respectively. This addon works by taking the tag that is selected and putting all cards with the subtag hierarchy into subdecks with the same name in alphanumeric order. For example, tag A has A::1 and A::2, where 1 and 2 are subtags, and if a card called MyCard has both tags A::1 and A::2, then since it goes in alphanumeric order for making tags, the card called MyCard will be in the newly created subdeck called A::2, not A::1.
After installing this Addon, go to the Tools menu > tag to decks > select your tag to make subdecks out of.
This addon is really geared for decks that are all the same deck hierarchy and have a multitude of tag hierarchies in them, like AnKing.
New feature:
The progress bar I promised earlier is done. Now, during the deck-making process, there is a progress bar showing which tag it is working on for making into a deck.
Once you see the window stating that deck building is complete, click the "ok" button, and that window and the progress bar will disappear, allowing you to see your deck and use it.