Elder Sign: Grave Consequences - Rules of Play says:
Grave Consequences expansion for Elder Sign introduces fifty new cards in three modular decks: Phobia, Epic Battle, and Epitaph.
- Phobia cards give investigators lasting negative effects.
- Epitaph cards build a tiny graveyard for the fallen.
- Epic Battle cards ramp up the difficulty and danger when battling the Ancient One.
All three of these decks and their cards can be used together or separately, and they’re all fully compatible with the core game, as well as all of its expansions.