Trundle pillar, pinning against a wall.
Pretty sure this is a bug, but just had a game where the enemy trundle managed to cast pillar in such a way that it literally pinned me against a wall. Tried multiple move commands and my champion (sona) did nothing. Ended up have to burn a flash so as to not be "stunned" for the full 6 seconds.
Suggest looking into niche situations where pillar displaces targets into walls, thus rendering them psudo-stunned.
(this got posted to TFT bug report by accident)