Not sure if you have tracked down the text or not -- or even if you still need it. Here it is, just in case:
Invincible Force Field wrote:
Setup: 7 Twists.
Twist: Stack this Twist next to the Mastermind as a "Force Field."
Special Rules: To fight the Mastermind, you must also spend 1 [Recruit] or 1 [Attack] for each Force Field next to them.
Twist 7: Evil Wins!