We just got ambushed in a courtyard by about 15 enemies standing on a walkway above us, with no immediately obvious way for us to get up there. We were sitting ducks. So Shadowheart cast blade barrier across the entire walkway. In addition to doing a lot of damage every turn, it imposes difficult terrain. All of the enemies stopped firing on us and tried to run to the end of the walkway. Most of them died on the way, but a few seemed to realize it was futile and turned around to run back and attack us, they died on the way back. A single concentration spell turned a dire situation into a complete bloodbath for our enemies. Shadowheart doesn't shine very often, but when she does, she shines like a diamond.