the rare lex luthor has this trait
PART OF MY PERSONAL INVENTORY: Once per game, give Lex Luthor a power action to place a special object whose name includes "Kryptonite" from outside the game into an adjacent square.

can he use it when a resource is on you force

Maybe. I don't know yet.

I think they said YES to this as the kryptonite you are adding to the game is from "Outside the game", and as such not part of your build.

(I could be wrong though.)

Wrong!!!

The correct answer is - Perhaps. There's a good chance we will know for sure someday.

i seem to remember them saying yes as well.