Aatrox Counter Tips
Applying Grievous Wounds to Aatrox will make him almost 50% weaker then what he is, so if you are on the same lane with him an item that applies Grievous Wounds is a great choice.
Another great thing to do against Aatrox is building attack speed reduction item since most of his damage comes from autoattacks.
His passive is resource bar dependent which means that if his resource bar is low he will revive at much lower hitpoints amount, so wait for the perfect moment to engage him.
Aatrox Dark Flight's spell will knock you up only if the you are in the middle of the impact.
Full damage build Aatrox can be really dangerous in late games, so try to focus him first especially if his passive is on cooldown.