Monsters, Mist, and types of metal.

For the newbies who joined the site, I'll give you some background info that'll help you with your characters.

Monsters -
Monsters varie from the evil "take-over-the-world" type to the small ones that appear cute... and are just downright evil on the inside. Monsters reform constantly over a short or long time period after being killed by demi-gods from the depths of Tartarus, and constantly come up from tartarus into Earth to attempt to fight one of the more stronger demi-gods. The more powerful the demi-god is, the more monsters the demi-god attracts - except for Aphrodite campers. Monsters tend to stay away from those and leave them alone.
Also, Medusa is considered a monster... so if you see a garden emporium with life-like statues, don't say I didn't warn you.

Mist -
Not the type of mist that happens outside. It's the type that obscures a mortal's vision to their understanding - so if you were having an epic fire battle they'd see it as simply a very large gunfight.

Metals -
Stygian and celestial bronze.
Celestial bronze is light, and makes great armor for demi-gods. But for celestial bronze weapons, it can't kill mortals - mortals are just too unimportant for the celestial bronze to pay attention to them, and doesn't kill them. Celestial bronze can kill monsters, though, and occasionally wound gods if you can get close enough...

Stygian - it comes from the underworld, that always is a black and depressing colour. Usually only Hades children wield this, hence it comes from the underworld.