Molten Boulder

Launch a boulder of flaming hot magma that knocks back your enemies.

Molten Boulder is the Druid's level 6 Elemental skill, requiring Firestorm; it unlocks Fissure. It is a cast that rolls a boulder along the ground: everything it collides with takes physical and fire damage and a knockback, it leaves fires behind it, and when it stops or meets something it cannot push it explodes. The numbers that decide it are the two damage lines, 130–155 physical plus 130–155 fire at level 20, and the cost, 19.5 mana at level 20 with a one-second casting delay.

The numbers

• Physical damage is the MinDam/MaxDam columns: 6–12 at level 1, then +4/+5 a level to level 8, +7/+8 to 16, +10/+11 to 22, +13/+14 to 28 and +16/+17 past that (MinLevDam1–5 and MaxLevDam1–5). 48–63 at level 10, 130–155 at level 20, 260–295 at level 30.
• Fire damage is the EMin/EMax columns with exactly the same base and brackets, so the two lines are equal at every level.
• Fire damage per second from the lingering fires is a tooltip line that reads the missile table and is not in the repo's bank, so it is not in the table above. The Basin's page prints the fire's bit rate, 40–56 at level 1 and 560–576 at level 20, and its display formula, 3 fires × bit rate × 25 ÷ 256: about 12–16 fire a second at level 1 and 164–169 at level 20. The Basin warns that this displayed figure is computed as though +% fire skill damage applied to it, and it does not.
• Explosion radius is Param1 = 7 (aurarangecalc par1), which the Basin gives as 4⅔ yards.
• Casting delay is localdelay 25 frames, 1 second at every level. The Basin notes it was 2 seconds and global in the older game, and is 1 second and local in D2R.
• Mana is 10 at level 1 and 0.5 more a level (mana 20, lvlmana 1, manashift 7): 14.5 at level 10, 19.5 at level 20, 24.5 at level 30.

The damage lines read lvl, so +skills from items raise them; both synergies read hard points only.

How it works

Molten Boulder is a cast on your cast rate (Casting Speed) and cannot be used as a werewolf or werebear. The Basin's description: the boulder rolls for 50 frames (2 seconds) in D2R, twice the speed of the older game over the same range of about 14 yards, and applies its damage and Knockback every frame to targets it collides with, though its movement and the knockback mean any one target is hit far less often than that. The knockback is 50% and applies to small and medium targets; a target that is not knocked back is rolled through until the boulder expires. Knockback is away from the caster's current position, so moving after the cast can push targets out of or back into the path. The boulder explodes on expiry and on impact with large targets and anything that cannot be knocked back: physical and fire damage are applied within the radius and 18 fires linger afterwards. The physical damage goes through Dealing Physical Damage, the fire through Dealing Elemental Damage.

The boulder's own damage and knockback can be blocked (Blocking); the explosion's damage cannot.

Synergies and +skills

Two synergies, on different halves of the damage: Volcano, +12% damage per level (Param7, "Physical Damage synergy", through DmgSymPerCalc = skill('Volcano'.blvl) × par7), and Firestorm, +8% fire damage per level (Param8, "Fire Damage synergy", through EDmgSymPerCalc = skill('Firestorm'.blvl) × par8). Both read hard points only. The Basin records the older Volcano value, 10% a point. Molten Boulder's own hard points are a synergy for Firestorm (+23% fire a point), Fire Claws (+22% fire a point), Volcano and Armageddon.

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 Molten Boulder against players.

Build notes

• Half the hit is physical, so it goes through fire immunes and Volcano's +12% a point raises that half; the other half is fire, raised by Firestorm's +8% a point.
• The Basin's rule that continuous casting at close range can roughly double the damage per second against targets that are repeatedly knocked back is the case for casting it on top of the pack rather than from range.
• Mana climbs 0.5 a level with no cap: 19.5 at level 20, 24.5 at level 30 with +skills, every second.
• Its hard points feed Firestorm, Fire Claws, Volcano and Armageddon, which is most of the reason to put more than one point in it.