Theory on Sion's Reboot and Gangplank's GU
So I've been thinking... We didn't get any reworks/updates for Sejuani, Ashe, and Trundle until the Lissandra patch came out for the Frelijord event. We also didn't get any reworks/updates on Cassiopiea until just recently when the Shurima event was launched. So doesn't it stand to say that we could possibly get the Sion (and possibly Gangplank) update(s) on a Halloween event? This is all circumstantial, of course.