While Androxus is channeling Reversal, take the time to reload your weapon, switch targets for a moment, or escape if needed, as it's detrimental to you to attack him during this time.
It's highly probable that Androxus will Refersal and then Nether Step away from combat when in danger. After that, he's mostly a sitting duck, because you probably still have your movement abilities and he doesn't.
When an Androxus activates Reversal and you have fired to much already, dodging around makes you a much harder target to hit. Also, if you want to deal damage, and you have an AoE attack ability, aim slightly in front or to the side to hit him.
Force an Androxus into a long range fight. For example, if you are playing Kinessa, and an Androxus sneaks up behind you, teleport to a distance, and open fire from there. He will either have to fight if he does not have Nether Step or run.
Good aim will take you a long way on this champion. Learn his range. Always have an escape plan. Understand how to win every matchup (will come with time). Use your mobility!