This is an auto-include if you’re running spirit in Heirs of Numenor and Against the Shadow. The majority of the quests have shadow cards that do this to the player, so having a free means to effectively cancel the extra damage is amazing.
Tides of Fate
Response: When a shadow card increases an enemy's by any amount, increase the defending character's by 3 for that attack. Then, the players as a group may spend 2 resources to ready the defending character and give it +3 for its next attack this phase.
The Return of the King
Flight of the Stormcaller #7. Spirit.