If Galen was caught off guard by her not lecturing him, he didn't let it show. Nor did he let her words of complimenting how skilled he was and impressed she was affect him. He was certain a lecture or warning would come after their duel about the Force lightning. But he wasn't going to let himself get caught off guard again. He summoned his saber back to his hand and activated it, the blue blade humming to life.
"It was gain the skills or die trying to learn them," he replied calmly. And it was true. With Vader, things like mercy didn't exist. He kept his eyes and senses open in case Mara tried anything. But she really didn't have to worry about him and the Force scream. He didn't even know what that was let alone how to use it. But he did have other tricks up his sleeve.
Slowly and as subtlely as he could, Galen began drawing the Force in. He started moving towards Mara, slowly at first then quickly dashed in. Once again his lightsaber turned off and he drew his arms and legs in as he floated in a sphere of Force energy. Loose objects on the ground started floating around him before he suddenly expanded his limbs, releasing the Force repulse. It had saved his life numerous times on missions when he had been swamped by enemy numbers.