Firestorm → Molten Boulder → Fissure → Volcano → Armageddon

The Fire Druids focus on the left side of the Elemental skill tree where the fire-based skills are. This is very similar to the Windy Druid, except it's not as popular due to several factors. Firstly, the last fire skill, Armageddon, as a prerequisite, requires the last Wind skill, Hurricane. Which, in turn, requires all the other Wind skills. So effectively, Armageddon's prerequisites are every other Elemental skill, which requires five skill points to invest in the wind skills. It's not much, but it makes a difference. However, the exceptionally high synergy bonuses can easily compensate for this, resulting in much higher damage. It's true that many monsters in Hell difficulty are immune to fire, but Molten Boulder and Volcano still can do a good job.

If you like fire, don't hesitate to make a Fire Druid, they can be very fun to play - and it's much easier to handle the first few acts with fire than with wind because wind skills are more effective at higher levels.

Because fire-based builds are difficult to use in Nightmare and Hell, any fire-based Druid will be primarily for play in Normal difficulty. In allied multiplayer games, the fire-immune monsters can be dealed with by your allies, still leaving a massive share for you in combat with other monsters. One effective version, however, uses a combination between Dire Wolves and Fissure. The wolves (plus mercenaries) are used to bog the enemy down, while the Druid casts Fissure, which does exceptional constant damage for its level. Hilariously, this is very effective against Act Bosses, and can be used to kill tough monsters like Duriel before they even harm the player, so long as the Druid remembers to summon more wolves as they begin to die.