Diablo II: Lord of Destruction/Elemental

Elemental Arts
Mimicking his comrade the sorceress, a druid may cast two of the four major types of elemental damage--fire and ice--as well as spells that harness the power of wind. These skills do not require that a particular enemy monster be the intended target, and they all have the ability to do damage to multiple foes. As a result, a druid specializing in elemental arts will shine most brightly against crowds of enemies.

The most powerful elemental arts use quite a lot of mana; fortunately, among the summoning and shape-shifting disciplines are skills that allow the druid to recoup mana from enemy creatures, both alive and dead.

Firestorm
While this spell is ineffective against single opponents, especially at medium to long range, it is quite effective against crowds of enemies at close range. It needs no particular target and can be fired onto any visible piece of ground. Aim it behind oncoming groups of enemies, and the fire tendrils will snake through the group, causing damage to each creature they come in contact with.
 * Description: Sends tendrils of flame along the ground, damaging any enemies it contacts
 * Level prerequisite: 1
 * Skill prerequisite: None
 * Mouse button: Left or right

Molten Boulder
The fiery boulder created by this spell rolls from the casting druid in the direction of the attack. A creature need not be targeted, so attacking a piece of ground beyond the intended target(s) is most efficient. A small delay between castings will prevent the druid from having more than two molten boulders in play at any one time.
 * Description: Rolls a burning globe of magma, causing knockback damage
 * Level prerequisite: 6
 * Skill prerequisite: Firestorm
 * Mouse button: Left or right

Arctic Blast
This unusual spell lets the caster determine how long the spell will be cast; as long as mana holds out (and you hold down the casting button), Arctic blast will hold forth. Better yet, the spell can be swept in any direction--just aim while it is activated to freeze enemies on all sides. This spell is best used when you're with a party or summoned creature that can administer damage while the enemy crowds are immobile.
 * Description: Emits a gout of frozen air at enemies in front of the character
 * Level prerequisite: 6
 * Skill prerequisite: None
 * Mouse button: Left or right

Fissure
This spell can be directed at any piece of ground, preferably beneath the scampering feet of a crowd of enemies, who will all suffer fire damage in a region near the casting target.
 * Description: An area attack that causes fire damage by cracking open the earth's crust beneath enemies
 * Level prerequisite: 12
 * Skill prerequisite: Molten Boulder
 * Mouse button: Right

Cyclone Armor
This spell acts like a disposable piece of armor, which absorbs fire, lightning, and cold attacks until it can no longer do so. Its longevity is roughly indicated by the number of swirling blobs of light surrounding the character--as the armor wears off, the number of blobs drops from three to zero.
 * Description: A personal aura that protects against all elemental damages except poison
 * Level prerequisite: 12
 * Skill prerequisite: Arctic Blast
 * Mouse button: Right

Twister
This spell can be targeted at the ground and will affect any enemy that it contacts along the way. Affected enemies are stunned for a duration based on the skill level. This spell can be activated with the left mouse button and requires relatively little mana, so it is suitable as a primary attack.
 * Description: Sends a small group of whirlwinds on an erratic course from the druid to the target spot
 * Level prerequisite: 18
 * Skill prerequisite: Cyclone Armor
 * Mouse button: Left or right

Volcano
A druid can summon a volcano on any open piece of ground. Enemies near the crater receive instant damage, but enemies all around the site are affected by the magma that drops from the sky as well. Cast volcano in enemy groups, and put the target point on or near the toughest foes.
 * Description: Pops a hole in the ground, through which globs of magma erupt and fall to the ground on all sides
 * Level prerequisite: 24
 * Skill prerequisite: Fissure
 * Mouse button: Right

Tornado
While tornadoes do a respectable job of hitting their target, they do not always make contact, due to their erratic motion. It is possible to have multiple tornadoes in motion at one time. This spell can be activated with the left mouse button, and requires relatively little mana, so it is suitable as a primary attack, especially when combined with the solar creeper, which drains mana from corpses.
 * Description: Creates a funnel cloud that moves generally in a straight line from the caster to the target point
 * Level prerequisite: 24
 * Skill prerequisite: Twister
 * Mouse button: Left or right

Armageddon
A devastating area-effect spell, armageddon's rain of fire follows the druid as the druid moves, until its duration runs out. A short delay between castings prevents more than two of these spells to be active at once. Any creature or piece of ground may be targeted to activate the spell, but the fire damage will occur only in the vicinity of the druid.
 * Description: Brings fire damage down from the skies around the casting druid
 * Level prerequisite: 30
 * Skill prerequisite: Volcano, Hurricane
 * Mouse button: Right

Hurricane
A hurricane may be cast at any target or piece of ground but will always activate itself around the druid himself. This spell will follow the druid as he moves, letting him sweep the spell's effects through large crowds as well as simply enjoy the effects of the spell on surrounding monsters while he fights hand to hand.
 * Description: Envelops the druid in a swirling storm that damages all nearby monsters
 * Level prerequisite: 30
 * Skill prerequisite: Tornado
 * Mouse button: Right

Shape-Shifting
Strictly a personal skill, shape-shifting lets a druid transform himself into a wolf or bear creature and then apply skills particularly suited to each of these types of beings.

Werewolf
As a werewolf, a druid's attack speed, attack rating, life supply, and stamina are all increased. When used in conjunction with lycanthropy, feral rage, and other skills, this skill enables the druid to transform into a fearsome melee fighter. To leave werewolf form, cast werewolf again--this returns you to human form. In were form, a druid cannot cast elemental skills.
 * Description: Transforms a druid into wolf form
 * Level prerequisite: 1
 * Skill prerequisite: None
 * Mouse button: Right

Lycanthropy
Players tired of re-shape-shifting will want to sink a few skill points into lycanthropy, as will hardcore players who focus on shape-shifting.
 * Description: Bumps up the amount of time that a druid can stay in were form and augments the druid's life supply
 * Level prerequisite: 1
 * Skill prerequisite: Werewolf
 * Mouse button: Passive

Werebear
Much like werewolf, this spell changes the druid into another form that has increased life and defense and dishes out greater damage. Werebear is not as nimble as werewolf but is hardier. To leave werebear form, cast werebear again (or werewolf)--this returns you to human form. In were form, a druid cannot cast elemental skills.
 * Description: Transforms a druid into bear form
 * Level prerequisite: 6
 * Skill prerequisite: None
 * Mouse button: Right

Feral Rage
The strength of feral rage is indicated by the blob of orange light that orbits the werewolf; the brighter the blob, the more powerful the effects of feral rage. After a short time without attacking enemies, feral rage will subside to nothing.
 * Description: An attack that becomes ever more powerful as the druid, in werewolf form, strikes enemies
 * Level prerequisite: 12
 * Skill prerequisite: Werewolf
 * Mouse button: Left or right

Maul
Much like feral rage for werewolf form, this skill's strength is displayed in the guise of an orbiting globe that brightens as the werebear defeats enemies. If no enemies are slain within a short time period, maul will fade away.
 * Description: An attack that becomes ever more powerful as the druid, in werebear form, slays enemies
 * Level prerequisite: 12
 * Skill prerequisite: Werebear
 * Mouse button: Left or right

Rabies
Spread a plague among the foes by attacking with rabies, which causes a chain-reaction poison attack to spread throughout the attackers. Any poisoned foe will transfer that poison to anyone it comes in contact with. Because poison takes time to have full effect, and because of this spell's unique plague-like characteristic, a werewolf with rabies should attack multiple targets in an enemy crowd, using his stamina and speed to dart around the edges of mobs.
 * Description: A werewolf attack that poisons not only the target but also any enemies who brush up against the target
 * Level prerequisite: 18
 * Skill prerequisite: Feral Rage
 * Mouse button: Left or right

Fire Claws
This attack may be used with either form of were creature. It affects only the target creature, not those surrounding it.
 * Description: A were attack that not only adds fire damage but also boots the attack rating of a changeling druid
 * Level prerequisite: 18
 * Skill prerequisite: Maul
 * Mouse button: Left or right

Hunger
At a tremendous cost to damage, this attack returns life and mana to the druid for each hit scored.
 * Description: A were attack that trades in damage benefits for life- and mana-leeching benefits
 * Level prerequisite: 24
 * Skill prerequisite: Fire Claws
 * Mouse button: Left or right

Shock Wave
Not to be used as a primary attack, shock wave temporarily stuns all opponents close to and in front of a werebear, letting it strike with impunity. Its high mana cost and low damage makes it a skill that should be used in conjunction with some other attack, like fire claws or maul. When assigned to the right mouse button, shock wave does not need a specific target; when assigned to the left mouse button, it does.
 * Description: A wave that emits from a werebear, stunning all enemies in its path
 * Level prerequisite: 24
 * Skill prerequisite: Maul
 * Mouse button: Left or right

Fury
Much like a paladin's zeal skill, fury lets a werewolf attack two or more targets with a single click. If only one target is available, all attacks will be unleashed on it alone.
 * Description: Increases attack bonuses for a werewolf and automatically attacks multiple times
 * Level prerequisite: 30
 * Skill prerequisite: Rabies
 * Mouse button: Left or right

Summoning Skills
Increasing the number of minions in your party can never hurt, and this branch of the druid's skill tree does that in spades. Some minions directly attack the enemy, while others augment the druid's already existing skills and life and mana supply. All minions (apart from the airborne raven) serve to distract enemies at no cost to the druid's personal health, making them very useful to players who dislike, or cannot afford, dying.

Certain summonings can cancel previous summonings; for example, a druid may have active only one type of vine (poison creeper, carrion vine, or solar creeper), one type of spirit (oak sage, heart of wolverine, or spirit of barbs), and one type of ground creature (spirit wolf, dire wolf, or grizzly). Ravens are not dispelled when wolves or bears are present.

Vines creep along behind their druid, performing their particular skills at their own discretion. Spirits tag along, casting their helpful auras on any party member near enough to be affected. Summoned creatures generally follow the druid but choose their own targets, and they will often attack without waiting for the druid himself to make contact.

Raven
Ravens cannot be damaged by enemies, thanks to their wings, guaranteeing that when you summon them, you will benefit from their attacks. A raven can also attack across gaps where wolves and grizzlies cannot roam.
 * Description: Summons a raven (or more than one, depending on skill level) that attacks a certain number of times before vanishing
 * Level prerequisite: 1
 * Skill prerequisite: None
 * Mouse button: Right

Poison Creeper
This low-level vine is most useful in the early game and against enchanted monsters, since poison damage doesn't take full effect immediately. Most players replace the creeper with more powerful vines when they can do so.
 * Description: A vine that does poison damage to its own targets
 * Level prerequisite: 1
 * Skill prerequisite: None
 * Mouse button: Right

Oak Sage
A high-level oak sage is a tremendous boon to a party, especially a group of hardcore characters. An oak sage needs a moment before its life-giving benefit takes effect, but when it does, it automatically fills each party member's life globe as it increases the maximum life level. A powerful oak sage can make a high-level character extremely difficult to kill.
 * Description: A spirit that boosts the life level of the druid and all members of his party
 * Level prerequisite: 6
 * Skill prerequisite: None
 * Mouse button: Right

Summon Spirit Wolf
A spirit wolf makes a good early-game minion, but more advanced creature-summoning skills will likely take its place once they are available.
 * Description: Calls forth a spirit wolf, who assists in a druid's attacks
 * Level prerequisite: 6
 * Skill prerequisite: Raven
 * Mouse button: Right

Carrion Vine
This vine sucks the last bit of life out of corpses and gives it to the druid. This ruins the corpses for necromancers (who can raise the dead as minions) and barbarians (who can search the dead for potions and items), and there is no way to directly unsummon a carrion vine. However, summoning a poison creeper will cause the carrion vine to disappear, and the creeper has no effect on corpses. A carrion vine requires an unshattered corpse in order to be effective, so bear this in mind when using such a vine while you attack with cold damage.
 * Description: A vine that consumes fallen enemies and transfers the life to the casting druid
 * Level prerequisite: 12
 * Skill prerequisite: Poison Creeper
 * Mouse button: Right

Heart of Wolverine
This skill is primarily for offensively minded druids who wish to augment the attack rating and damage of all party members. Only one spirit may be present at a time, so summoning this spirit will cancel all others.
 * Description: A spirit that boosts the offensive skills of a druid and his party members
 * Level prerequisite: 18
 * Skill prerequisite: Oak Sage
 * Mouse button: Right

Summon Dire Wolf
The dire wolf is a tougher version of the spirit wolf and will assist the druid by attacking its own chosen targets. It's a good minion for the midgame, until the grizzly becomes available, and it may be a better choice if you prefer the multiple minions provided by playing more skill points into dire wolf.
 * Description: Calls forth a dire wolf, who assists in a druid's attacks
 * Level prerequisite: 18
 * Skill prerequisite: Oak Sage, Summon Spirit Wolf
 * Mouse button: Right

Solar Creeper
This vine is more sentient than the carrion vine, which feeds on corpses regardless of the druid's health. A solar creeper will wait to feast on fallen enemies until the druid requires mana. This vine is especially beneficial to druids who use mana-intensive spells like hurricane and armageddon. Switch to carrion vine when life, not mana, is in short supply.
 * Description: A vine that sucks the mana from corpses and adds it to the druid's supply
 * Level prerequisite: 24
 * Skill prerequisite: Carrion Vine
 * Mouse button: Right

Spirit of Barbs
Much like a paladin's thorns skill, spirit of barbs harms any enemy that successfully causes damage to a party member.
 * Description: A spirit that reflects damage back at attacking enemies who score hits on party members
 * Level prerequisite: 30
 * Skill prerequisite: Heart of Wolverine
 * Mouse button: Right

Summon Grizzly
Truly a ferocious comrade, the grizzly absorbs the toughest onslaughts while his druid summoner assists him with spellcasting. Grizzlies stay alive better than any other summoned creature. Alas, it's only one pal and it may not occupy an entire group of enemies like several dire wolves may. Purchase a hireling at camp to assist the powerful grizzly if you're attempting the game alone.
 * Description: Summons a grizzly bear, which assists in a druid's attacks
 * Level prerequisite: 30
 * Skill prerequisite: Summon Dire Wolf
 * Mouse button: Right