If you've signed into Discord lately, you might've seen one of a number of bots offering the promise of free stuff in exchange for an invite to your server. As you might've guessed, these are fake, and will do some nasty stuff to any server they get into. Discord is working on "long-term mitigations" for these spammers, but you'll need to stay vigilant in the meantime.
One of the more notable scams masqueraded as an official Twitch bot, promising free Discord Nitro games - which Discord no longer offers - in exchange for a server invite. According to ShaxxMotivation on Twitter, this bot would DM every user in a given Discord, ban everyone, and then delete all channels there. And, of course, no free PC games would arrive.
These scams have been prolific for a few weeks now, and they're not just under the Twitch name. The Discord subreddit is full of examples of the bots, but in short: don't trust any bot promising free stuff, especially if the promo is full of obvious spelling and grammar errors. You might see some bots with 'scam' or 'fake' in their names - as they get banned, Discord mods are changing the bot names to warn users against fakes.