Luthor held the tiny sliver of synthetic kryptonite up to his eyes.
"Such a tiny thing," he mused. "To look at it, one would think it was just a trinket. A pretty but utterly inert thing. They could never imagine the power concealed within it." He sneered down at the doll in the box. "Remind you of anyone?"
The doll was silent and immobile, staring up at him with shock frozen on its plastic face. Luthor peered closer and, as their eyes met, he imagined he saw a feeble flicker of red trying to burn in those painted-on eyes.
He flicked the glowing chunk into the cardboard box, bouncing it off the doll's hard plastic tits. It came to lay on the velvet base. As its emerald light washed over the toy, the doll somehow became even more inert than before, its plastic skin taking on a glossier sheen. The definition of its face faded until its features were mere paint adorning the front of its head. The plastic cracked along the limbs, crude ball-and-socket joints forming.
"You'll have plenty of time to ruminate on my victory," Luthor sneered. "Consider this. Beyond its delightful effect of rendering Kryptonian bodies into artificial forms, the most wonderful feature of artificial kryptonite is that I can create more of it. This is only a small piece but Lex Corp has the capacity to scale up production to bulk quantities. In a year, it will be in everything - Lex Corp lunchboxes, Lex Corp drinking straws... we'll add it to fuel as an anti-knocking agent. In a year, I'll free you. Then you'll have to decide whether to fly away and leave Earth to humans, or stay here on a polluted planet, forever a doll."
With a deep, smug cackle, Luthor reached into the doll's body, grasping its tiny torso in his fist, and gripped one plastic limb between his thumb and forefinger. With five quiet pops, he disassembled the doll. "See you in twelve months, Superman," he laughed, sealing the doll in darkness.