Under-druids

U is for Under-druids, distorted, subterranean versions of their more familiar, arboraceous brethren.

Tied to the dark and stone, rather than the moon and forests, the under-druids draw power from the stone, and twist it to their needs.

source

Under-druids (spec'ed here for S&W, with some add-ons borrowed from 3.5) share many characteristics with druids, modified for their subterranean environs. Deviations and modifications are noted below:

Prime Attribute: Wisdom and Constitution, both 13+ (a druid character gains a +5% experience bonus only if both their Wisdom and Constitution are 13 or higher.)

Hit Dice: 1d6/level (Gains 1 hp/level after 9th.)

Armor/Shield Permitted: Leather or bone armor and wooden shields only.

Weapons Permitted: Dagger, hammer, spear, sling, oil. Stone or stone-bladed weapons, if wielded by an under-druids may be treated as magical weapons.

Race: Any humanoids may become Under-druids.

Alignment - Any chaotic

Because of their disconnection from the world above, an under-druid does not require mistletoe as a spell/powers component. Instead, they utilize a variety of fungi, many of a hallucinogenic nature. In fact, they are likely addicted to them, resulting in a somewhat addled nature.  However, this also increases their sensitivity to the currents of the world around them, and they may cast an augury (as per 3.5) once per day.

Under-druids gain a +2 saving throw bonus against petrification.

Under-druids share most elements of the druidic spell list, except as noted below:
They do not have access to any weather-related spells, and plant-centered spells are substituted with either fungus/oozes, or stone.

Level 1

• Detect Magic
• Detect Snares & Pits
• Faerie Fire
• Locate Animals
• Predict Weather
• Magic Stone (as per 3.5 spell)
• Purify Water
• Stone Fists (as per 3.5 spell)

Level 2

• Call Stone (as per 3.5 spell)
• Create Water
• Cure Light Wounds
• Heat Metal
• Locate Plants Fungus
• Obscuring Mist
• Produce Flame
• Speak with Animals
• Warp Wood 

Level 3

• Call Lightning
• Cure Disease
• Hold Animal
• Neutralize Poison
• Plant Fungal Growth
• Protection Against Fire Petrification 
• Pyrotechnics
• Stone Shape (as per 3.5 spell)
• Water Breathing

Level 4

• Animal Summoning I (summoned animals limited to subterranean types)
• Control Temperature 10-ft. Radius
• Cure Serious Wounds
• Dispel Magic
• Hallucinatory Forest Stones
• Insect Vermin Plague (calls creeping, flying, scuttling mass of cave vermin)
• Plant Stone Doorway (created passage through stone wall, only accessible by caster)
• Produce Fire
• Protection from Lightning
• Speak with Plants Fungus and Oozes (may communicate with fungus, as well as oozes/slimes/jellies up to under-druid's HD)

Level 5

• Animal Growth
• Animal Summoning II
• Anti-Plant Fungal and Ooze Ward (Protects caster from fungal attacks, as well as oozes/slimes/jellies, 10' radius)
• Commune with Nature
• Control Winds
• Hold Plant Fungus and Oozes
• Transmute Rock to Mud
• Passplantwall (as 5th level MU spell)
• Sticks to SnakesStones to Spiders caster may turn as many as 2d6 normal stones into large (1HD) spiders (lethal poison, +2 save).
• Wall of Fire Stone (as per 3.5 spell)

Level 6

• Animal Summoning III
• Anti-Animal Ward
• Conjuration of Fire Earth Elementals
• Feeblemind
• Finger of Death
• Repel Wood Fungus and Oozes
• Transport via Plants Stones
• Weather Summoning Stone to Flesh (as per 3.5 spell)

Level 7

• Animate Rock
• Confusion
• Conjuration of Earth Elementals
• Control Weather
• Creeping Doom
• Fire Storm Meteor storm (as 9th level MU spell)
• Reincarnation
• Transmute Metal to Wood Earth (transmutation of metal to soil in a 10x10 area

Update: Gavin Norman commented on G+ that he'd made up some spells specifically for a druid such as this.  Here, here, and here. Thanks!