Suppose you're editing a card and click "Cancel", or your browser crashes, or you leave or close the page without saving. Wagn will have saved what you're working on so that you can recover it later.
When you're editing cards, a few times a minute Wagn saves a draft. If you never click "Save", then the draft remains available, and if you look in the card's history, you'll see something like this:
From there, click on "Autosaved Draft" to see the draft, and if you want to update the card to be that draft, then click on "Save as current".