Very simple Nasus change that would make him a tad healthier to play against
Give his Q a longer cooldown, and in exchange increase how many stacks he gains on each q so he can still at least stack at the same rate he can now assuming free farm, if not more depending on whether you think he needs a direct nerf or not since increasing his Q cooldown would be nerfing his damage output aside from how many stacks he is able to get.
Doing this would provide his lane opponents a little more room to punish him for greedy stacks, as they would have more time to harass him before they have to worry about getting smacked by another q. It would also reduce his synergy with Sheen/Triforce and thereby lessen his mid-game power spike and make him to be a little more actual late game oriented, as he always was supposed to be originally.