He doesn't do much, just shifts his stance so he's more likely to stay on his feet. After a second's thought, he murmurs, "Come, Satan."

His mask disappears, revealing tense eyes and a stubborn, angry jaw. Satan appears in a flash of blue fire, in all his... well, glory is one word for him. "Just testing," says Ren. "Seeing if I can keep him summoned through the attack." Assuming he doesn't just die, obviously. "I'm good to go whenever."