How much longer is Shiv allowed to be a burst mage/Assasian/Tank

So we've all probably played that game where Shyvana goes full ap and becomes a wall hoping one shotter. This i may understand if she was at full build, but instead all she needs is a and her , not only does it her empowered e do over 1000 damage, but it has a huge hitbox that completly anihaltes anyone relitivly close to where she used it. All while still being harder to kill then any other mage/assasian at least in terms of hp/tankiness. I had a 15/3 zed on the other team with 4 items and i was still more afraid of the 2 item 3 kill shyv