Ironman
#Knickstape
Already been shot by that it didn't kil himPoint is if he's the smartest man on earth he would've ended superman a long ass time ago. He's like batman, he's messy and loves the drama.
If he truly hated that nikka he would've smuggled something toxic to kryptonians in his food or manufactured kryptonite bullets with metallo's help and then let that thing spray. Supermans dumb ass would be like "guns? Really lex you know those bullets will just bounce off" before them bullets kick through his spinal like Bruce Lee.