Quick question about ingame magic pen

No, it breaks it up into flat and %. It appears as though you currently have 46 flat magic pen, plus 0%.

Items like void staff give you % mag pen while items like your boots and torment give you flat. It would be impossible for them to convert your flat to %, as 46 mag pen would be a different % against every enemy.

Flat pen works better against people that aren't stacking MR, while % is better against teams that are stacking it. On a side note, isn't there a mastery that gives % mag pen....and why don't you have it lol?

Flat mp is much more powerful, than percentage one. Amount of mr, that is taken into account when dealing damage is effective mr= mr*%mpene-flat mpene