Katarina shunpo and GankPlank Barrels.
Just saw this little bug when playing with a Gankplank as a Katarina. When Katarina Shunpo's to an ally Gankplank's Barrel, she will Autoattack it but deal no dmg. This hapens whn you just shunpo to it, without pressing any other commands after the spell cast. Katarina will continue to Autoattack the barrel, but it will do nothing.