|A huge mace imbued with potent fire magic. It fills those it strikes with inner flame, and offers protection against the resulting devastation as well as immunity to clouds of flame.|
+7 great mace
Unless you're facing foes resistant to fire, Firestarter is an exceptionally powerful weapon, combining a solid and well-enchanted base weapon, a decent brand, an extremely useful defense (any source of rF++ is worth consideration), and one of the most brutal melee crowd-control methods in the game. That being said, its downsides are very significant. The amount of noise you'll be producing in combat will awaken many nearby monsters, so expect reinforcements to be a constant threat. Also, many of the major sources of fire damage in the game are resistant or immune to fire damage themselves, making the weapon a useful defense against them, but not exactly ideal offensively speaking.
Prior to 0.19, Firestarter did not grant immunity to clouds of flame
Firestarter was added in 0.14.