No merit Pool but Token pool.
you earn Token not Merit
Ok, this makes more sense now. That's not as prone to merit abuse than I originally thought. The campaign itself doesn't deal with merits so that's good. Participants would be inclined to earn merits even if they already have a high rank. Some might resort to shady ways of getting those merits, but overall this is probably better than a typical rank-based campaign where you could just enroll with a bought account and shitpost away.
And I don't think this will work. Most bounty participants have 0 merit, because their posts aren't worth it. I'm also pretty sure many bounty participants use many different accounts, and if they have higher hevels, they have sMerit to give. That would mean they can merit their alt accounts, to earn more tokens from the Token pool.
Once the "airdrop" sMerits run out it won't be easy to merit their alts. The OP can come up with some restrictions to discourage alt-merits, e.g. ignore merits sent between campaign participants. Might be harder to track though.
