"Some card generate Willpower Counters (WC). WC can empower other cards and may be expended in the process." -- In-game description of WC
Willpower Counters (WC) are counters added by certain cards. They appear as a blue drop next to the characters avatar. A blue number on the drop represents how many WC there are. Certain cards require WC to activate their effects, and can make them dangerous. WC can also be taken from an opponent by the effects of certain cards.