[Bug][Item] Luden's Echos procs for only 20 damages

I wanted to try the Luden's echo buff a number of times on different assassins like Akali or Katatina, how ever it was procing for only 20 damages. I added a video on you tube I uploaded. The Proc does 20 damage because it get's increased by it's own large rod ( 20x1.2=24 then magic resist 24x0.83=20) Visible at about 40 seconds in the video.

Then Chogath got hit for 17 damages because he had Zephyr for a total of 40 magic resist 24x0.714=17 Visible at about 46 seconds.