What can I use Card Block for?
The Power-Up first needs to be enabled for a given board. To enable, please go to Settings - Power-Ups - Card Block and tick "enable".
Blocked cards cannot be moved, they have a distinctive look and optionally display a message, explaining why they have been blocked.
So now, if there happens to be a problem with progressing work on a specific card, the card can get blocked until the problem is resolved and work can go on further along the board.