Clank! Catacombs

[Ihmejakumma]

What does this card mean, and how should it be used? Game: Clank! Catacombs.
"When a Ghost would damage you, you may discard this to prevent that and draw a card

[Sirhk]

When a ghost cube is drawn from the bag during dragon attacks (or other player's turns, if they've escaped/died) then if this card is in your hand, you can discard it to not take any damage and draw a replacement card.

No reason not to use this effect unless you're building up damage for some reason like reaching the 5 damage threshold to purchase the blood amulet from the market.