Cards can be categorized into 4 different types:
1: No ability: This type of card does not have abilities, but it usually has higher power than others at the same cost.
2: On reveal: The card's ability will be triggered once revealed.
3: Ongoing: The card's ability will be continuously active after it is revealed.
4: Special abilities: The card's ability is conditionally active, even without play and reveal. For example, Angel's ability will automatically activate when one of your cards has been destroyed, and it will replace that card, or Bishop has a trigger that means he will get buffed for every card you play but it's not an "Ongoing" card.