It's hard to measure exactly what combination of factors result in him at least partially slipping his binds. Maybe its Blanche's distraction, or maybe it's the warmth and direction of the gem cradled in his palm. Either way, when he sees Greg go flying, he lashes out instinctively. He doesn't think about whether or not he can do it, he just tries.

It turns out, he can.

The strength of his blue magic pours through the stone and through to the rest of Greg's soul, enchanting its gravity and catching him before he can hit the ground, a soft glow surrounding the musician's body.