For the amount of potential damage Nasus deals, his increase over timne slow is a bit long
I get he needs the slow to be combat effective with most of his potential his damage more or less loaded into his auto buffing Q, but 35% up to a 95% slow over 5 seconds is pretty strong given his massive damage potential with his Q stacks and his ability to get an entirely tanky build (not to mention his ult and his armor shredding E).
I don't want to hurt his playability too much, since he is kinda straight forward, but maybe lower the slow by some or reduce its duration by a couple seconds would seem fair.
and
are common nasus items, also
if not FG. All of these help him chase or slow fleeing targets.