Corruption
Corruption cards represent the dark influence of the mythos upon the investigators. There are two types of Corruption cards: green Corruption cards are generally less severe, while red Corruption cards can spell doom for one or all of the investigators.
Corruptions were introduced in the Black Goat of the Woods expansion.
Corruption rules
When a player is instructed to draw a Corruption card, he or she draws the top card of the Corruption deck and places it near his or her investigator sheet. An investigator may have more than one Corruption card at a time.
Every Corruption card has an effect that is triggered whenever a particular monster movement dimension symbol appears on a mythos card during the Mythos Phase. There are two versions of every Corruption card in the deck: one with a dimension symbol on a white background and one with a dimension symbol on a black background. Effects on Corruption cards do not trigger unless both the symbol and the colored background on the Corruption card matches those of the mythos card drawn during the Mythos Phase. Triggering a Corruption card ability is not optional.
Corruption cards are resolved immediately after monster movement during step 3 of resolving a mythos card. Some Corruption cards also have passive abilities that are always in effect. For example, the card 'Endless Greed' has both a passive effect and a triggered effect. The passive effect of 'Endless Greed' (the text that appears above the monster movement dimension symbol) is always in effect as long as the investigator has that particular card.
When a gate is closed, all Corruption cards in play that match the closed gate's dimension symbol are discarded. Certain card effects may also instruct a player to discard cards off the top of the Corruption deck. Discarded Corruption cards are placed in a discard pile and are considered removed from the game. The Corruption deck is never reshuffled.
If a player is instructed to draw a Corruption card, but there are no cards available to draw, the Ancient One immediately awakens.
List of corruptions
| Corruption | Type | Activation |
|---|---|---|
| Call the Beast | Green | 
|
| Creeping Doom | Green | 
|
| Downward Spiral | Green | 
|
| Endless Greed | Green | 
|
| Jealous Guardian | Green | 
|
| Nightmarish Visions | Green | 
|
| Primal Surge | Green | 
|
| Speak to Your Friend | Green | 
|
| Fate and Fortune | Red |
|
| Mental Paralysis | Red |
|
| Ruination | Red |
|
| Strength of Flesh | Red |
|
| The Skin Crawls | Red |
|
| Uncontrollable Rage | Red |
|
| Vessel of the Mythos | Red |
|
| Weakness of Mind | Red |
|
Errata
The rules say to stack 8 green and 8 red cards to form the corruption deck. You are supposed to use all 16 green and 16 red cards.
