Kamikaze Dwarf

As its name says - kamikaze. The dwarves are of main reasons to have fire resistance. They carry (at least) a backpack of black powder and a religious book of (random?) god. Since they cannot see invisible, invisibility is one of the better ways to deal with them. Fire resistance is also a useful alternative, but you still risk wand explosions and equipment loss.

Kamikaze dwarves also make interesting pets. With their gunpowder taken away, they tend to beat enemies with their holy books.

Without any means to protect yourself against kamikaze dwarves, you can easily expect to be blown to pieces when the danger level is high enough :)