And Cassiopeia loses yet another way for her to build magic pen

So now the ONLY way for me to build flat non % based magic pen on Cassiopeia is to build a full 3100 item ?

And even if I build that 1 item, I can only sit at a max 15 flat magic pen all game? I already know there is no way Riot can balance base MR with Cassiopeia's inability to build MPEN boots, the lack of any starting MPEN as Cassiopeia, and other burst mages being able to build early MPEN.