A need to have card if you're running Thurindir and side quests. I've seen this card deal up to 6 damage before and I know that it can do more. But I never use this card when not running a side quest deck. Also, keep in mind that this includes encounter side quests as well, not just player side quests.
My opinion:
When Running side quests: 9/10
When not running side quests: 2/10