Go for Ravel!

"Neat trick, but I'm still well within my abilities to fight. You didn't damage me that much, and we got in a lot of hits on you..." Rias growled at Riser, perparing to blast again. "And you used up a lot of magical energy to pull that stunt."

"True, but not enough you stand a reasonable chance of wearing me down before I damage you enough to **** your retirement," Riser sighed, rubbing the back of his neck, before turning to Ravel. "Finish the Pawn, then come help me deal with Rias."

"Ugh, he's so beneath me, but fine," Ravel whined, before walking up to Issei, who had the **** beginnings of a plan forming. If he could just get close enough to her to use Dress Break... Unfortunately, Ravel didn't seem interested in close combat, and instead started pelting him with little fireballs.

"Argh!" Issei grunted, taking a step back. He then rushed forward, tanking the burns, but Ravel jumped back, taking to the air, hovering about ten feet above Issei.

"Like hell am I letting you get a hit in!" she declared, throwing a bigger fireball at Issei, who dodged. He turned his head to see Riser attacking Rias, ignoring all attempts to counter from her, as he coud heal. They were basically trading blows, Power of Destruction vs Phoenix Flame. Riser was losing more willpower, but Rias was accumulating damage at a faster rate, and without Asia to heal her, she couldn't keep this up for long, burns starting to spread on her body.

Knowing he had to act immediately, Issei brought out his wings, and flew right up at Ravel. Before she could dodge, he pushed some power into his gauntlet. "Dragon Shot!" he shouted, using the explosive spell as propulsion instead of an attack. It rattled his body a bit, and drained nearly all of his remaining stamina, but he got the intended result. He grabbed her by the front of her shirt.

"Ack!" she yelped, preparing another fireball, before her eyes widened as she saw Issei give a shit eating grin, his other hand raised to snap. Remembering what had happened to Isabela, her eyes widened. "Don't you da-!" she started to demand. Too late.

"Dress Break!" he shouted, snapping his fingers, making Ravel's garb disintegrate, and he immediately looked intently, seemingly eyeing her up, before he moved his hand, as if to grope her.

"EEEEEEEEK!!! YOU BASTARD!" she screamed, blasting him at point blank. He was flung back to the ground, and cratered it slightly as she panted, and conjured up more flames to serve as a makeshift bra and panties. "Hah, get up from that, you damn perv!" she declared to the smoking crater.

"Okay~!" Issei replied cheerfully, casually walking out of the smoke like nothing happened. Ravel's eyes practically bugged out when she saw that his injuries were all gone.

"What the fuck!? How!? Your healer is retired!" she demanded, pointing accusingly at him, before her eyes widened again as he held up his left hand, a very familiar vial held between the inex finger and thumb of the gauntlet. Realization hit her like a ton of bricks. That Dress Break was meant to make her drop the Phoenix Tears, and when she had thought he was trying to grope her, he was actually quickly catching them before they could fall, and had clearly managed it before she had blasted him.

Issei exhaled, before carelessly tossing the fancy vial away. "You REALLY shouldn't have told me about those," he gloated, before mentally calling to Ddraig, initiating the deal. He cried out in pain as his arm suddenly began to convulse, becoming clawed within the gauntlet, and growing red scales. The ones on his hand were hidden by said gear, but the effect spread up his arm, and stopped at his shoulder.

"What have you done?" Ravel asked, slowly edging back in the air, wary.

"I made a bargain," Issei replied simply, flexing his new arm, testing it. "Oi, Ddraig, you mentioned a time limit?" he then asked, ignoring Ravel, much to her indignation.

"Yes. At the time I presented the offer to you, your body was strong enough for ten seconds with my power. Now that you're fully healed, and stronger than you were at the time, you almost doubled that. 18 seconds. That's how long you have to end this," Ddraig answered, and Issei grinned. That was plenty.

"Then let's do this!" he shouted, channeling all the power Ddraig had to lend him. "Shine! Overboost!" His body glowed, and armor formed around it. "Balance Breaker Boosted Gear, Scale Mail!"

"Shit!" Ravel screamed in fear, charging up a large fireball. Issei however, didn't give her the chance. He leapt right at her, so much faster than before, and grabbed Ravel by her wrist. Instead of striking her, and making his body phase though her flame, he turned several times in the air, and yeeted her as far away as he could, her screaming all the way, getting a distance that would have Koneko green with envy.

He then turned, and flew through the air at Riser from behind as he was starting to overwhelm Rias. "Hey KFC!" he roared, grabbing him by the back of his head, and dragging him away with the momentum. Rias, wheezing, blinked and looked after them in surprise, and hope.

"Damn it!" Riser growled, trying to process what was happening. Issei then slammed him face first into the courtyard ground, dragging him along it, and using Riser's face to carve up a nice deep, flaming trench, before letting go, and jumping back. "You commoner trash!" Riser growled, getting up, his face reforming. He turned, and his eyes widened as he saw Issei bend down, and casually scoop up both the Holy Water and the cross with his left hand. "...what? How are you handling that cross!?" Riser demanded, taking a cautious step back. The Holy Water, he could understand, so long as it was in a container meant to contain the holy essence, handling it was uncomfortable for a Devil, but not debilitating until contact with the water itself. The cross however was a different story. Even this armor shouldn't protect him from that! He then widened his eyes in realization again. "Your arm... you gave it to the Dragon!?" he stammered.

"Exactly. My arm is no longer that of a Devil's, but a Dragon now," Issei replied as Ddraig told him 16 seconds left. It was actually kind of funny. He'd once mocked how long five supposed minutes took in one of his anime series, and thought the explanation that those who could move, and percieve things faster than humans could basically make seconds seem like minutes through perception, was a bit of a weak one. Now though, he was experiencing it first hand. Everything was slow motion to powerful entities like Devils when they exercised their full power.

"You fool! You do realize it will never return to your original arm, don't you? Even with Rias's new powers, the Red Dragon is powerful enough that she won't be able to undo such a deal struck with him!" Riser asserted.

Issei shrugged. "One arm for the ability to protect Rias? Sounds like one hell of a bargain to me," he replied. "Besides, even if she can't make it human, or Devil again, I'm pretty sure nothing in the deal states she can't at least make it look human for casual life. Besides, having a dragon arm? Badass as hell. I'm really not seeing any downsides here."

"You're crazy!" Riser grit his teeth, now truly terrified of Issei. "I'll just have to destroy you with all of my power!" He got ready to charge, wreathing himself in flames once more.

"And just how much do you have left?" Issei taunted. "After all those hits we landed on you, blowing a lot of it on that desperation move of yours, and then fighting Rias until I could snag the Phoenix Tears from Ravel... you're close to empty at this point, aren't you?"

Riser roared, and flung himself right at Issei, fear, fury and desperation in his eyes.