Buffing Aatrox. (W) opinion.
His (W) Infernal Chains have potential, but it's very weak versus mobile champions (most of them in games). This changes can solve most of problems:
If chain hit champion, their movement skills will be blocked for 1.5 seconds. Slow: 10 / 14 / 18 / 22 /26 (slightly down)
Enemy still can leave area and don't take bonus damage and being dragged. Aatrox will have good counter vs mobile champions, not mobile champions have better chances vs (W).
Some thoughts about his ultimate ability (R) World Ender: This skill must deal something more for Aatrox or versus his opponent. Changes:
(R) can ba activated anytime, even in CC (except if he is suppressed). Don't give CC immunity, just break options.
or
(R) fear enemy champions for 0.5 sec as well. If enemy run from AA range, Aatros still have (Q)+(E) to deliver his rage.
P.S. New Aatrox don't need a lot changes, only 1 from this list can make him better in game-play.