Screenshot via Game Guides Pro Back 4 Blood is Turtle Rock Studios’ latest co-op shooter and one with a fair share of new mechanics for players to explore, including a system that upgrades known in-game enemies. under the name of corruption cards. Corruption Cards are modifiers that dramatically improve the Ridden in Back 4 Blood campaign. At the start of each level, players are given several corruption cards to select from. Each will improve their enemies in different ways. Players can always check which Corruption Cards are active at the start of a level just above the Active Cards menu (pictured above.) Related: How to Get Mutation Points in Back 4 Blood Some of these cards from Corruption offer rewards if players complete levels with Reinforced Ridden while under the effect of these buffs, such as a large amount of Copper to be spent on upgrades in the next level store. Be prepared for a challenge when activating these cards, as the Ridden gain strength with each card. Make sure you read what the Corruption Map does before you apply it, so you are aware of the dangers ahead. Back 4 Blood is out now for PlayStation 4, PlayStation 5, Xbox One, Xbox Series X | S, and PC To learn more about Back 4 Blood, be sure to look at our other articles, like Back 4 Blood Supply Lines Explained here at Guides.