**Random theory alert based on his skills.
So he killed zed first which could mean that his Q ability is a headshot that leaves a trail of flowers inside the targets head and everyone knows that flowers have roots, so maybe his Q is a damaging spell with a root?
Second person to die was Sona who got shot in the throat so maybe his W is a silence on an a enemy as well as a speed boost due to the air and butterfly's coming out of her?
Third one to die is Garen and it stated that "Jhin" could pierce the armor of a mighty hero so maybe his E is a true damage ability or it just ignores massive amounts of armor?
Then Vi died last and she was the only one that was 100% confirmed dead, so maybe his R is a skill where it will execute an enemy that is under a certain threshold and if they are above that threshold rather than getting executed then they get disarmed for a certain amount of time?
His passive is not quite clear to me yet but maybe he can control the elements for example if he is in the river he is controlling the water element and gets some kind of move speed, if in brush he controls nature and gets an added slow because of applying vines/roots to his target, the element of fire is a tricky one my only explanation is that his ult could give him a fire aura that causes his attacks to deal bonus fire damage, maybe its a passive on his ult as well as an active - could also be if he has red buff he gets more buffs on top of the red, but explaining the wind / crystal is tricky, maybe because of crystal he gains armor/magic resist as he levels and the wind could give him an out of combat move speed buff?
If i'm completely wrong here i don't even give a shit because I've just invented a fucking champion! Peace.**