Unfortunately I have no video proof but I'm sure it will happen if you try to reproduce.
Basically if you ult as Karthus you'll target dead people as well (how come!?) and if that person spawns before his ult cast is over, he will take damage. The question is, how can you target dead people with skills? Makes no sense to me.
Is there something you really can't do without in the client? Is Udyr displaying as a Picasso painting again? This is the place to report bugs and give suggestions for League of Legends in general!
Don't spam your suggestions or bug reports here, and follow the [Universal Rules](http://boards.euw.leagueoflegends.com/en/c/announcements-en/3eWpXbJi). While not every suggestion here will be implemented, your favourites can be voted to the top for maximum visibility!