For Agnes, this card can be even better than simply canceling an attack. When you are up against a big baddie, she can choose whether to cancel their attack or allow 1 horror to go through in order to return 1 damage to them.
Fast. Play when you are dealt damage and/or horror.
Cancel up to 10 damage and/or horror just dealt to you. Exile Devil's Luck.
I haven't tried it yet, but if you were to take Parallel "Skids" O'Toole, with his tiny deck to The Dunwich Legacy, this card could be a good counter to Beyond the Veil, which could potentially be a significant issue for him. You could lose it to a discard treachery before you draw it, but even then, you might be able to get it into your hand by drawing an or playing Eucatastrophe. If you draw enough s or do some Double, Double + Scrounge for Supplies shenanigans, discarding cards from your deck might actually be a good thing.
The issue with this one is that it is exceedingly rare to be dealt around 10 damage and/or horror in a single instance (the poster child being Beyond the Veil).
Perseverance covers real-world cases at a cheaper XP cost.