I'm not sure there is a way to advertise on Discord. You may be able to advertise on a specific persons discord server.
To find out if you can promote an offer on a discord server, you have to submit that question for each offer you want to promote. Simply go to the offer page in MaxBounty, and there will be an option for questions about promoting the offer. Usually they tell you on the offer page where you can and cannot promote it.
I am pretty sure that discord is more of a gaming network. I am in one of the chats and I do not think that the participants are really into ads. They are mostly teens and do not like buying stuff not related to gmes. If you really want to get their attention then promote things to do with video games.
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