I was wondering a few things also.
First, with his passive, can it be interrupted? Because he will be a counterjungling monster where you have to rush down a camp before his passive takes it.....but it does look like a channel. I also don't understand how it interacts with smite; can i smite a grove that is still growing to instantly "kill" the camp or does it need to be a full grown grove? and can my opponent do the same? The numbers on the pbe also seems weird, the health and mana costs don't scale up but instead jump around.
His W is confusing me also; the video (champion reveal) has him casting it 3 times in rapid succession despite, at best, a 24 second cooldown (unless that is just a typo).
Finally, his E. Does it function like sion's shield where if the shield is consumed before it detonates it does not detonate? or does the explosion occur no matter what?
Overall though, a cool champion with some unique skills/aspects.