Look these images, you are totally wrong. Lb is at 20% or more, istant dies and trow the fireball. He doesnt explode where he stands.

griffin just used ultimate and CUT some hp to lb. Witch already has orbs ready
Here lb is just using his ultimate, no other ability can be cast, the screen gets dark and he use utimate, he still have same amount hp
Here lb just used ultimate and gets killed by witch damage 13k.you still can see the solar beams falling down from the Sky.
He dies istant, no dot, no other damage. Only 13k by witch, it is enought to kill him. And he fires fireball.
Here you can see the solar beams still on and the fireball going to my group.
I can post video too but i dont know how do it.
Images are anyway clear, you can see all you need.
Ucool i am waiting an answer