It's funny how this has been an ongoing problem for years and now that it's affecting the top two leagues, it's time to do something serious about it. I don't disagree that something needs to be done, but I'm not a fan of using 50% of the entire reward pool to support this. The lower leagues have taken the brunt of every nerf so far and are barely earning anything as-is. Giving up 50% of that is massive.
As far as suggestions go...
First, good faith means nothing and there are people in this community that have already proven that.
Second, just because an account holds an Archmage or Xbot token doesn't mean they're using it all the time, if at all.
Third, checking for people playing bot teams? Seriously?
Fourth, not only have bots proven their ability to bypass captcha, players with less than stellar internet connections will suffer if this is implemented. Personally (and I know I'm not the only one), I always have problems with captcha. Sometimes I can never get it to work and sometimes it takes 15 tries. Flees due to captcha fails is going to be an issue.
Finally, here are some things I suggested 6 months ago. What about locking out the battle API and only allowing access to whitelisted 3rd parties? Companies offering bot services could be charged a hefty fee for access which would make the service cost prohibitive unless they implemented or raised their own fees. A lower earnings incentive should lower the number of people willing to use the service and the people that continue to use the service will offset the lower number of users with higher fees.
Eliminating back door access for anyone to submit scripts directly to the API may not be perfect, but it'd definitely put a dent in things and we wouldn't have to mess with the reward pools to do it. Alternatively, a -50 to -75% penalty to rShares for people scripting the API on the back end could be another solution and also help to lessen their affect on the reward pools.
Lastly, there's always KYC. It's not the perfect solution, but it would still have an impact on larger farms. A combination of increased fees for API access, penalized back door API scripting, and KYC would be a huge step in the right direction.