Mercenaries are the rough warriors of the underground. They can fight with iron gear and can bare ores from the land.
The Mecenary is a class with iron gear and mining abilities. This can be very useful for a guard post, and mining jobs.
The best income for the Mecenary is to mine and/or kill monsters at night.
Tips for playing Mecenary:
1. Fight in groups. You can fend off monsters alone, but players don't go down so easily.
2. Try to avoid fighting pvp-classes alone. They have access to better gear than you, and can easily beat you.
3. One way to earn gold is to get gatherers and such to hire you as a personal guard while mining, travelling, etc. The other is the tedious, old mining.