Recently, my own Discord server has happened to be a target of the same Discord spam-bots that the Idle Empire is suffering from.
All of the bot accounts share similar characteristics, though it is still hard to nitpick them until it is too late and they already post their stuff or DM people.
Being on Guard and insta.banning new coming members based on those specifics can be exhausting for staff and lead to false bans - of people who look like bots.
In my server, we solved this out with making every member upon joining simply react to a message, which gives you a role that lets you see all channels.
Without the role, the bots are completely cut out and cannot even access the member list = no DMing people. And yes, they are too dumb to react to it.
After implementing this, the bots actually turn beneficial to the server, as they boost the member count and sit there whilst completely isolated and harmless. :D
/// How to:
To do this, you simply set-up a new role, that is given to every member and holds permissions to read/see all voice&text channels...And disable the ability to see all text&voice channels for everyone without the role.
The Idle Empire already has a role that everyone has, the "Rookie" role to which you can give these permissions.
It would just have to get changed to be given upon the message reaction, instead of instantly upon joining.
Once a user joins, he sees only one channel where he is prompted to react to the message as an anti-spam measure, which unlocks him the whole server that he can then enjoy.