Alot of people are saying its Jhins abilities that we are seing in the teaser video but what if its him having hallucinations?
RiotUtora said on Reddit: "Oh maaaaaaan. I literally can't WAIT for you guys to hear his VO (Voice Over). Seriously, it's kind of hurting me."
When asked: "hurting u as in a funny way or a scary way?"
He replied: "scary way. dude is super creeper. never before have i had to take some mental steps away from a champion due to their personality and demeanor before."
So what he is saying is that Jhin is basically a psychopath. So my theory is that the things happening in the teaser arent actually his abilities but him having hallucinations. What do I mean by that you ask? Well what if when he kills someone he sees those beautiful things; flowers, butterflies, roses etc. but in reality its actually blood and gore? The description of the video says "I will make you beautiful. I will make you perfect.". So in his reality he is not killing them but actually making art out of them which would explain the title of the video "the **MIND **of the virtuoso". A virtuoso is an individual who posses outstanding technical ability in a particular **ART** or field. The art of killing someone in a particular way so he gets the most beautiful hallucination out of it? Who knows...
But in the end its just a theory so everything I just stated might be completly wrong. Let me know if you liked my theory or not and feel free to add something to it.