active defending effect的用法和样例：
- Every stack has its own turn periodicity. After activating Defend, the stack gains +30% to Defense until the next turn, and the time to wait until the next turn is halved.
- It is also able to defend arcs made by inverted rubber.It makes the ball back driving too untraceable to defend effectively.
- Design on an active defending system for e-government infosec
- Actively defended, a citadel will hold out for a very long time.