Skill

Amazon	Assassin	Barbarian	Druid	Necromancer	Paladin	Sorceress
Javelin and Spear Passive and Magic Bow and Crossbow	Martial Arts Shadow Disciplines Traps	Warcries Combat Masteries Combat Skills	Elemental Shape Shifting Summoning	Summoning Poison and Bone Curses	Defensive Auras Offensive Auras Combat Skills	Cold Spells Lightning Spells Fire Spells

All classes begin game with the following common skills, which cost no mana to use:
- Normal Attack (with any weapon excluding throwing potions)
- Throw (with throwing weapons and potions)
- Unsummon (unsummons pets)
- Scroll of Identify (in inventory, identifies items when used)
- Scroll of Town Portal (in inventory, casts town portal when used)
Assassin and Barbarian alternate between two weapons when using Attack; they both only attack with their right hand when bare-handed and equipping no shield.
Barbarian can also use Left Hand Throw when equipping throwing weapons or potions.
Necromancer begins game with a +1 Raise Skeleton Wand.
Sorceress begins game with a +1 Fire Bolt Short Staff.
Many skills use missiles, the properties of which can have a significant impact on their performance.

Skill points

Each class also has three of their own skill trees, each containing 10 skills: these skills can be learnt and then used by investing skill points. Characters receive one skill point each time they gain a character level, and skill points can also be awarded once in each difficulty level for completing the following quests:

Act	Quest	Giver	Point(s)
1	Den of Evil	Akara	+1
2	Radament's Lair	Template:D2 Unique dropped by Template:D2 Unique	+1
4	The Fallen Angel	Tyrael	+2

A maximum of 20 points can be invested in each skill. Points can only be invested in a skill if points have been invested in its prerequisite skills and if the sum of required skill level and points already invested is less than or equal to character level: while some skills are available at level 1, others only become available at levels 6, 12, 18, 24 and 30. For example, an Amazon cannot invest a point in Freezing Arrow until she is level 30 and she has invested points in its prerequisite skills Cold Arrow and Ice Arrow, and she may not invest another point until she is level 31.

Respecialisation

Skill (and stat) points can be reset as a reward from Akara for completing the Den of Evil quest in Act 1 once in each difficulty level. Characters who completed this quest in all difficulty levels before 1.13 will only receive this reward in Hell.

Skill (and stat) points can also be reset by transmuting all four of the following items in the Template:D2 Unique to create a Template:D2 Crafted, then using that token:

Item	Source
Template:D2 Crafted	Template:D2 Unique
Template:D2 Crafted	Template:D2 Unique
Template:D2 Crafted	Template:D2 Unique
Template:D2 Crafted	Template:D2 Unique
Template:D2 Crafted	Template:D2 Unique

Buffs and debuffs active at the time of the reset will remain active until they expire.
Native Offensive Auras and Defensive Auras active at the time of the reset will no longer be applied but their graphic will still be displayed, as will their former effects in the character screen. However, this display error stops upon exiting the game and everything returns to normal at the start of the next game.

Skill bonuses

Although characters can only invest 20 points in each skill, their level can be increased further by applying various skill bonuses:

Individual skills (class-specific and Oskills, allow skills to be used without investing points if character level >= required level)
Individual skill trees (class-specific)
Individual class skill levels (class-specific)
All Skills

Certain items also apply bonuses to Fire Skills only:

Item	Bonus	RLvl
Template:D2 Set	+1	11
Template:D2 Unique	+1	23
Template:D2 Unique	+1	27
Template:D2 Unique	+2	21
Template:D2 Unique	+2	22
Template:D2 Unique	+2	65
Template:D2 Unique staff	+3	19
Template:D2 Unique	+3	33
Template:D2 Unique	+3	71

Amazon	Assassin	Druid	Necromancer	Paladin	Sorceress
Fire Arrow Exploding Arrow Immolation Arrow	Fire Blast Fists of Fire Wake of Fire Dragon Tail Wake of Inferno	Firestorm Molten Boulder Fissure Fire Claws Volcano Armageddon	Corpse Explosion Fire Golem	Holy Fire	Fire Spells

Active skills

Active skills require an action to be taken to use them. All active skills require mana to use, with the exception of the common skills mentioned earlier, Sacrifice, level >12 Magic Arrow and level >8 Double Swing. Skill icons are red if they cannot be used, either due to lack of mana or a required item, an active Delay or because it cannot be used in town.

Buffs

Buffs are active skills which apply a positive effect to the user or to the user and their allies for a duration after being used.

User only

Assassin	Barbarian	Druid	Necromancer	Paladin	Sorceress
Burst of Speed Cloak of Shadows Fade Venom	Frenzy	Werewolf Werebear Feral Rage Maul Cyclone Armor	Bone Armor	Holy Shield	Frozen Armor Shiver Armor Energy Shield Chilling Armor

User and allies

Barbarian	Sorceress
Shout Battle Orders Battle Command	Enchant

Debuffs

Debuffs are active skills which apply a negative effect to the user's enemies for a duration after being used.

Amazon	Assassin	Barbarian	Druid	Necromancer	Paladin
Inner Sight Slow Missiles	Cloak of Shadows Mind Blast	Howl Taunt Stun Battle Cry Grim Ward War Cry	Rabies	Curses	Smite Conversion

Berserk is the only skill to apply a debuff to the user.

Passive skills

Passive skills require no action to apply their bonuses. Passive skills don't require mana to use, and only apply to the user or pet. Passive bonuses are based on both skill points invested and skill bonuses applied.

Amazon	Assassin	Barbarian	Druid	Necromancer	Sorceress
Critical Strike Dodge Avoid Penetrate Evade Pierce	Claw Mastery Weapon Block	Combat Masteries	Lycanthropy	Skeleton Mastery Golem Mastery Summon Resist	Warmth Fire Mastery Lightning Mastery Cold Mastery

Some active skills also apply passive bonuses: Summon Spirit Wolf, Summon Dire Wolf and Summon Grizzly all apply passive bonuses to each other.

Auras

Defensive Auras and Offensive Auras apply positive passive bonuses to the user or to the user and any allies, or negative passive bonuses to any enemies within their radius of effect, as long as the aura is selected on the right mouse button. Auras do not cost mana, with the exception of Prayer.

Oak Sage, Heart of Wolverine and Spirit of Barbs supply auras applying positive passive bonuses to the user and any allies within their radius of effect once summoned.

Synergy skills

Synergy skills apply benefits to other skills based on the number of points invested in the synergy skill. Skill bonuses do not increase synergy bonuses. Most synergy bonuses are mentioned in the skill description, but the following skills also apply hidden bonuses based on the number of points invested in them: Resist Fire, Resist Cold, Blessed Aim and Resist Lightning.

Using skills of another class

Each class can gain access to the skills of another by equipping certain items:

Certain missile weapons also fire Magic Arrow and Exploding Arrow when Normal Attack is used:

Fires Magic Arrows

Missile weapon	Level	Ladder	Rlvl
Template:D2 Set	1	No	70
Template:D2 Unique	3	No	13
Template:D2 Unique	5	No	26
Template:D2 Unique	11	Yes	65
Template:D2 Unique	20	No	39

Fires Explosive Arrows or Bolts

Missile weapon	Level	Ladder	Rlvl
Template:D2 Unique	3	No	15
Template:D2 Unique	5	No	27
Template:D2 Unique	6	No	49
Template:D2 Unique	7	No	33
Template:D2 Unique	13	No	71
Template:D2 Unique missile weapon	15	Yes	65

Act 1 Rogue Scout hirelings equipping Fires Explosive Arrows or Bolts bows will display explosions when using Normal Attack, but these explosions do not apply their fire damage.

Delay

Some skills apply a delay when used: while the delay is active neither that skill nor any other skill with a delay can be used. Nothing reduces the length of these delays but, since they begin at the action flag (the frame in the attack or casting animation in which the action is actually executed), increasing attack or cast rate will slightly reduce the interval between actions since the action flag will occur earlier in the animation: interval = action flag + delay.

Class	Skill	Delay (Seconds)
Amazon	Poison Javelin	0.6
	Plague Javelin	4.0
	Immolation Arrow	1.0
	Valkyrie	6.0
Assassin	Shock Web	0.6
	Blade Sentinel	2.0
	Shadow Warrior	6.0
	Dragon Flight	1.0
	Shadow Master	6.0
Druid	Werewolf	1.0
	Firestorm	0.6
	Werebear	1.0
	Molten Boulder	2.0
	Fissure	2.0
	Volcano	4.0
	Armageddon	6.0
	Hurricane	6.0
Paladin	Fist of the Heavens	1.0
Sorceress	Fire Wall	1.4
	Meteor	1.2
	Hydra	1.6
	Frozen Orb	1.0

The only exception is when skills with delays are cast by % Chance to Cast items: multiple skills with delays can be cast. [1] However, while the skill delays are not applied, an 11 frame delay is applied from the action flag: during this delay no active skills can be used, although Scrolls of Identify and Town Portal placed in the belt can be used. [2] [3]

This 11 frame delay does not interrupt an attack sequence if % Chance to Cast is applied during that sequence. The delay can be applied from the action flag of any individual attack in the sequence, so if it is applied by an attack early in the sequence then the delay may end before that sequence ends. If multiple attacks in a sequence apply % Chance to Cast, the delay is applied from the last attack in the sequence to apply it. [4]

Radius

Many skills (notably Curses and Defensive Auras and Offensive Auras) apply their effects in a radius of effect, specified in yards. However, internally radius is specified in sub-tiles, each of which is a 2/3 yard by 2/3 yard square (4 square feet).

Template:Image

The radius of most skills increases with skill level, but skills with a set radius have been labelled in the diagram above:

Skill	Radius
Skill	Sub-tiles	Yards
Terror	4	2 2/3
Decrepify	6	4 0/3
Iron Maiden	7	4 2/3
Attract	9	6 0/3
Redemption	16	10 2/3
Inner Sight	20	13 1/3
Slow Missiles	20	13 1/3
Conviction	20	13 1/3
Cloak of Shadows	30	20 0/3

Cloak of Shadows isn't labelled since its radius encompasses almost the entire screen, with the exception of a tiny portion in the top left and right corners.

References

Basic Skill Information (Arreat Summit)
Casting Delays (Arreat Summit)
Nefarius, Skills.txt File Guide (Phrozen Keep)
Onderduiker, % Chance to Cast and Curses Tests (Technical Discussion)