what does pay 1 mean? Captain Cold

82
Leonard Wynters
Cost: 4 Bolt
Legion of Doom,
Villains
While Captain Cold is active, your opponent must pay 1 to declare an attack.
What does the pay 1 refer to? Energy, Life?
Leonard Wynters
Cost: 4 Bolt
Legion of Doom,
Villains
While Captain Cold is active, your opponent must pay 1 to declare an attack.
What does the pay 1 refer to? Energy, Life?