There is a very annoying problem with the magmamancers: they tend to die very, very often. It seems that, if they are immune to fire, they are not immune to hot things. It does not always appear in the combat log, but my last dwarf, just after having killed a drider, was “caught in a burst of boiling swamp whiskey”. Seems like they should use only fire safe material flasks and backpacks, and/or find some way to immunize them completely against any kind of heat, not only fire (which is kind of weird, as fire's only danger is heat…). As they are, they are pretty useless, except to generate small amounts of fun (or bigger, if you use one in a squad of non-magmamancers).