The Fire Sorceress is known for extremely high Fire damage capable of killing players and monsters in only a couple of hits. With explosive Fireball and Meteor damage both her Single Target and Area of Effect are extremely effective. Like other single element characters though, she will be dominant in specific areas but struggle anywhere with Fire Immune Monsters, which unfortunately covers many areas in Hell.
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Having a Secondary Skill such as Frozen Orb can be extremely useful on a Hell playthrough, though a well-geared Mercenary can handle fire resistant monsters as well.
Leaf Is a fantastic Runeword to pick up on this Character as well as she progresses through Normal due to the +3 to Fire Skills.