This is a really bad solution, especially if it's the only thing you do to prevent botting. First of all, if we assume your magical client can stop all bots, why not simply disallow all other clients? Secondly, anyone more skilled can just analyze what your custom client does to authenticate itself and do exactly the same to authenticate their own client, thus also getting boosted exp/drops. Thirdly, even if not using the custom client was to cut your experience gain and loot in half, botters still would gain a lot by setting up bots on non-custom clients.
The fundamental thing needed to stop bots are unforgiving rules. To stop bots, botters must be permanently banned upon the first detection – if you don't do that you have no right to say "it is a fight that cannot be won" because you didn't even try to win.
Even if you don't know any advanced detection methods, unforgiving rules combined with manual checks and disallowing clients other than your own (it's just a layer protecting against less advanced botters) are sufficient to get rid of the majority of bots, as long as your playerbase is small enough. If players risk losing absolutely everything, they will think twice before using a bot, even if the odds of getting caught aren't too high.