Glacial passive is fine. The percentage of it occurring is not.
I shouldn't go 1-for-1 in a close fight VS an opponent only to have my 3-star Lucian still standing vs a 1-star Ashe with 2-piece glacial buff, and the 1-star ashe wins because she just perma-stuns my lucian for 12 seconds.
Its a goddamn 20% chance to happen, or so the tooltip says. At best, over the course of 12 seconds, Ashe should get one stun off. Maybe 2. 3 if she got her ultimate off, which she didn't because my lucian was a demon.
Either its not actually 20%, or this person just got extremely lucky. I'd go with the latter, but this happens ALL THE TIME.
Y'all need to check the calculation algorithm on this skill and make sure its airtight, because something's fucky if you ask me.