Blast the four of them

Weiss was quick enough to notice the hypno gun.

"What is th-" But she wasn't quick enough to avoid the blast.

Cardin smiled.

"Wait, is that Cardin?" Ruby called out, "Don't let him in! Yang's changing shirts!"

"Uh, yeah!" Yang called out, "And why is that asshole here!?"

"Because I want to try out my new toy," Cadrin said as he walked past the mindless Weiss who just let him go by her.

"WEISS!" Yang gasped, "Why did you let him in!?" She was in the process of pulling a shirt over her large braclad beasts, "Get the hell out of her assh-" She didn't get to finish her sentence before Cardin shot her with the ray. Her boobs jiggled as her arms shot down and she stood at attention, dropping her shirt in the process.

"Yang?" Ruby asked, "What happ-" she stood at attention as well.

"Well, I know this works." Cardin said to the room with three cuties all standing at mindless attention. They were all hit with the 'blank' setting, so they'd be like this for a while.

Cardin then snuck into the bathroom, where Blake was showering with her eyes closed. So Cardin zapped her next. She went blank as well, and Cardin drank in her naked form.

"Turn the shower off and follow me," he ordered. Blake obeyed. Now all four members of RWBY were standing blankly before him.