Hello, this is Nukella from Klaipedia.
For the past few weeks, frost pillar has been causing severe FPS drops especially coupled with prophecy.
Frost pillar seems to proc very often starting from a couple patches ago, coupled with the resist spam from prophecy causes severe FPS drops especially in GvG.
You can clearly see in in the video, I go from 40 fps to 5 fps after frost pillar.
This was recorded today.