Firestorm

Unleash fiery chaos to burn your enemies.

Firestorm is the Druid's level 1 Elemental skill, with no prerequisite; it unlocks Molten Boulder. It is a cast that sends three piercing missiles along the ground, each leaving a trail of fires that burn whatever stands in them. The tooltip's number is fire damage per second, 3–7 at level 1 and 107–125 at level 20, and the skill's worth as a synergy is as large as its own damage: it feeds four other fire skills at 8% to 23% a hard point.

The numbers

• Fire damage per second comes from the EMin/EMax columns, which here are per-frame rates in the table's units, through the tooltip's calc enms × 25 × 3 ÷ 256: three fires, each applying its rate every frame of a second. EMin is 3 at level 1, then +3 a level to level 8, +5 to 16, +7 to 22, +14 to 28 and +21 past that (EMinLev1–5); EMax is 6, then +3, +6, +8, +15 and +23 over the same brackets. The widening brackets show in the table: 17–21 at level 5, 39–45 at level 10, 69–80 at level 15, 107–125 at level 20, 271–303 at level 30.
• Missiles are calc1 = ln12 = Param1 3 + Param2 0 a level: always three, so the line is not in the table.
• Casting delay is localdelay 15 frames, 0.6 seconds at every level. The Basin's page records that in D2R the delay is local, Firestorm's own, where the older game made it global.
• Mana is a flat 4.

The damage line reads lvl, so +skills from items raise it; the synergies read hard points only.

How it works

Firestorm is a cast on your cast rate (Casting Speed) and cannot be used as a werewolf or werebear. The Basin describes the shape: three piercing missiles that travel for 40 frames (1.6 seconds), the central one straight at the target and the other two on more random paths, with a range of about 10 yards; each missile spawns a static fire in its third frame and every other frame until it expires, 19 fires each, 57 in all, and the fires are what apply the damage. The damage is Fire Damage, cut by the target's Fire Resist and raised by Fire Skill Damage, see Dealing Elemental Damage; no attack rating roll is involved.

The tooltip assumes three fires on the target. The Basin says each fire applies its rate for only 14 frames, but up to 5 fires can apply to a size 1 target, 9 to size 2 and 14 to size 3, and with a 0.6-second delay the skill is cast at least once a second, so actual fire per second can be up to twice the tooltip on a size 2 target and three times on a size 3 target.

The Basin's formula for the real rate is (missiles × bit rate × 14 ÷ 256) × 25 ÷ (delay + action frame), and it recommends casting at point-blank range so the trails cross the target. Faster Cast Rate raises how often the 0.6-second delay can be refilled.

Synergies and +skills

Two synergies at +23% fire damage per level (Param8 = 23): Molten Boulder and Fissure, which the table calls "Eruption" in the calc EDmgSymPerCalc = (skill('Molten Boulder'.blvl) + skill('Eruption'.blvl)) × par8, hard points only. Firestorm's own hard points are a synergy for four skills: Molten Boulder (+8% fire damage a point), Fissure, Fire Claws (+22% fire damage a point) and Armageddon; each of those pages gives its line.

Against players

A player's hit on another player is cut to 17% of its value (difficultylevels.txt PlayerDamagePercentVSPlayer) before anything else, see Player versus Player. The Basin's page says nothing more about Firestorm against players.

Build notes

• Forty hard points in Molten Boulder and Fissure are +920% on the fire; the two synergies are worth more than the skill's own levels past 20, which +skills from items supply.
• Hard points in Firestorm pay back into Molten Boulder, Fissure, Fire Claws and Armageddon, so the fire tree rewards maxing it even where it is not the main attack.
• The tooltip undersells big targets: by the Basin's counts, bosses and other size 3 monsters can take up to three times the listed rate.
• Mana is a flat 4 with a 0.6-second delay, so the cost is about 7 mana a second when cast on cooldown.