Vlast nods along as Isaac lists off the side effects. Invigorating was certainly a word for what he felt when he drew on the raw magic from lyrium. He wasn't sure if it was mutation if he could control his changes. And really, they simply turned back to his original form (albeit how he looked in his late adolescence), so maybe mutation didn't quite apply.

He makes a low, gurgling growl of a sound. Temporary was more than applicable, much to his chagrin. He'd been lucky when he found that part out; flying low and over water looking for some fish for his supper when suddenly he was small again and tumbling out the air. A few scraps of canvas and old ropes from a wrecked skiff preserved what little modesty Vlast could spare as he staggered sopping wet and apoplectic back to the city.

Vlast watches Isaac fiddle with the cigarette. The rest he more or less knows; lyrium is volatile, lyrium is used by mages and templars alike though to different ends, spying on supplies would probably yield vital information.

His stare and brow shoots up, missing the last second of the trick, yellow eyes meeting Isaac's, intrigued but also wary.

"...Speak your plan plainly."