Zhonyha's nerf

I feel like almost every ap mage puts zhonya's into their build every game. I feel like zhonya's should get nerfed so its more of a situational item and less of a must have since stop watch is also an item. I feel like the dmg from zhonyas should be nerfed from 70 to 45 or 50, I also feel the cdr should be removed from the item so it isn't up every fight, since there are multiple mage items that give cdr ludens, cdr boots,. BUt keep everything else the same. I think this way zhonyas wont just be used by every mage and they will have to give up dmg for the utility of the item. I think zhonya's potential to turns team fights speaks for itself. But if the item is more defensive and less offensive people may prioritize dmg over the item. I also think this may help assassins a bit since most ap items are very strong.