[{quoted}](name=JC DarkOmen,realm=NA,application-id=LqLKtMpN,discussion-id=V6xqtxA1,comment-id=00000000,timestamp=2016-03-16T19:33:10.064+0000)
That really defeats the purpose then. if they were just walking through a bush I'd put a ward down. I only ever bought Skirmishers for the reveal. It's been at least half a year because Chilling Smite is so much better in almost all circumstances, and now I give it another go only to find out it's useless? It's better to slow her so that I get a speed boost to catch up to her after the invisibility than to reduce the damage she's doing.
The purpose of Challenging Smite is dueling, not revealing someone. The whole "deal true damage throughout the duration while reducing their damage" is the point. The reveal is just so if they are near bushes or trying to juke they can still be easily attacked and followed.
As a side note, do you realize how utterly broken Challenging Smite would be if it did reveal through invisibility? It would make every single champion that relies on it completely useless if they did not have a several second long invisibility that they can use from a decent range away. And that means the only invisibility champions not ruined are Rengar (who still has even worse ult to run away but at least can still leap to murder) and Twitch (who is still utterly ruined if trying to use the invisibility near anyone). Riot's trying to move away from buying an item outright removing a champion from the game, and Challenging revealing through stealth would do so.
