Goomba is an All-In-One Discord bot, with 60 and counting commands and many features, such as the help if you typo a command.
It also has per-server configuraion (which includes the Mod-Log channel, the Announcements channel, the Welcome channel, a switch (true/false) for the welcome and goodbye messages, and the messages themselves.
You can change the prefix, too, but remember, the standard prefix is +.