Use your W when you get slowed by one of his skills/autoattack. This slow lasts long so better to clean it as fast as possible.
Dont stun him when he is casting ice wave, just dodge it and hit him meanwhile. He wont do anything to you.
When you see him using his nuke spell, get out of vision range, count to 5 and go back engage him in fight.
Dont fight him when you are lower than 50% hp, he use Lighting from around 400 units range that will kill you if you are not geared enough.