Sion Ult Bug.
As Sion if you use your Ultimate and spam either S or H you'll be able to stop in place and slowly move into any direction you want. I don't think this feature should be usable during Sion's ultimate hints the name "Unstoppable Onslaught". It could be used so turn directions if you miss
(
Uses Ultimate and chases after
, Nami uses flash and
repositions himself with this bug and seals
fate.)
There are many other scenarios this could be used in even though it is not a very game breaking bug but it is kind of a big deal if you take advantage of it.