Skills
Skills are the magical attacks unique to each character class in Diablo II. Skills are enabled by spending skill points, improve with more points, and the characters can find a wide variety of items too boost individual skills, whole skill trees, or every skill possessed by that character. Each character has 30 skills unique to their class, but a few of these skills can also be used by other classes if they have special equipment to enable those skills.
Starting Skills
All five classes in D2C and all seven in D2X begin with the same 3 basic skills. Attack, Throw, and Unsummon.
Throw works only when a stack of throwing weapons are equipped, and it will hurl the knife, javelin, axe, or other item at the selected target or location. Throwing weapons can also be used for melee combat, when the Attack skill or other melee range skills are is used.
Unsummon is only active when a character has summoned minions of some type (such as the Necromancer's skeletons/golems, the Druid's wolves/bear/spirits/vines, the Amazon's Valkyrie, etc), and when used it will dispel any summoned minion targeted.
These skills are not located in the skill trees, but are inherent skills all characters possess. Additional skills are available right from the start, as soon as a character gains skill points from leveling up from quest rewards.
Special Starting Characters
All characters start with a basic weapon and shield of some sort. These do enough damage to deal with the first monsters encountered, but should be upgraded as soon as possible. There are two partial exceptions to this rule. Since the Sorceress and the Necromancer are very weak in combat, they begin the game with weapons that grant them a level one skill.
- Sorceress begin with a staff that grants +1 to the Fire Bolt skill.
- Necromancers begin with a want that grants +1 to the Raise Skeleton skill.
These items are only useful to those character classes (another character could equip the staff or wand, but would not gain the skill bonus), and are simply +1 bonuses to individual skills (the same sort of mod that can be found on all wands and staves in the game). When a Sorceress or Necromancer gains a skill point, they can put it into Firebolt or Raise Skeleton, which will give them level 2 in those skills.
Unique Skills
All characters have 30 skills, sorted 10 each into 3 skill trees. These skills are unique; no two character classes share exactly the same skill, though many of the skills have at least partially overlapping functions. (For instance, all combat characters have skills that increase their damage and their attack rating, in various ways.)
Skills can be divided into two types; passive and active.
Active Skills
Active skills are ones that a player uses intentionally. They must be mapped to one of the mouse click button or a hotkey, and will only function when individually enabled. Most active skills are used in place of Attack, and enable your character to strike or shoot or throw or cast something at the monsters; something more effective than the default Attack skill would enable. Almost all active skills cost mana to use, of an amount that varies with the skill points.
Passive Skills
Passive skills work all the time, and do not need to be actively selected. Each point in a passive skill will increase a character's chance to perform it, or boost the effect of the skill. Most passive skills work only in certain situations; the Barbarian's six weapon masteries, each of which boosts his damage, accuracy, and critical hit % with one type of weapon. Swords, maces, polearms, etc. The Amazon's Dodge gives her a chance to dodge attacks, but only melee strikes, and only when she's standing still. Avoid does the same but only works against ranged attacks, and Evade only kicks in when she's walking or running.
There are exceptions to the rule, of course. Some skills blur the lines between active and passive. For instance, the Paladin's auras are passive in effect, boosting him continually when they are active, but they must be selected to the right mouse button to take effect, and he can only use one aura at a time (though it's possible to keep two in almost constant effect by dexterously switching between them every few seconds). Just putting points into an aura doesn't help the Paladin; he has select the aura on his right mouse/skill button to gain benefit from it. (There's a slight exception to that rule too, in that points in the Resist Fire, Resist Cold, and Resist Lightning add to his maximum possible resistances to those elements.)
Skill Icon Use
To select a skill to use, click the left or right icon on the game interface. This will pop up the icons for every skill that can be mapped to the left or right click. The skills allowed on the left and right are often different. As you can see in the two shots here, there are numerous skills this Paladin can use with the right click, but not the left. All of his Auras, but also Identify, Town Portal, Unsummon, and Find Item, a Barbarian skill granted by his equipment.
Some skills that can be mapped to the left or the right will work differently from one side to the other. Ranged attack skills, such as Multishot or Frozen Orb, will cast the spell/skill every time they're clicked on the right, but if set to the left will only function if a valid target is selected (or if they are clicked while the Shift key is depressed). Otherwise they will cause the character to run to the location clicked on.
It's recommended that characters set useful skills to both sides, once they are higher level. There's no point in leaving Attack on the left click with a mage character (most players pick direct target spells such as Glacial Spike or Bone Spear), and combat characters often use the left click for emergency skills such as Frozen Arrow. The left click can also be used as a sort of extra hotkey; stick a skill you'll only use in certain situations there, such as your combat character's best elemental damage skill.
Red Skill Icons
When a skill can not be used the icon will display red. This is usually caused by insufficient mana, but can also indicate that a skill is not available because the item that grants it is not equipped, because there's a casting delay, or because your character is in town and it can not be used there.
Skill Points
Characters begin at level one and earn a skill point each time they level up. There are also 4 skill points to be gained from quest rewards, on each difficulty level.
- Act One: 1 skill point rewarded by Akara for clearing the Den of Evil.
- Act Two: 1 skill point is gained by reading the Book of Skill, dropped by Radament.
- Act Four: 2 skill points are rewarded by Tyrael for killing Izual.
This results in a maximum possible skill point total of 110 at level 99.
Skill Maximums
Skills max out at 20 points, but they can be boosted much higher by equipment. Most well-equipped mage-type characters have at least +10 to all, and it's not uncommon to find characters with +25 (or more) to particular skill tree or skill. There is no hard cap on total skill points to any skill; the total is only limited by the equipment you can assemble. (A fact that various hacks and cheats have put to dirty use.)
Many skills gain less benefit with additional points, after some level. This is known as "diminishing returns" and it effectively caps those skills at some point. The Amazon skill Critical Strike starts out at a 16% chance to deal double damage, but each point in the skill adds less than the previous. It's worth 42% at level 5, 55% at level 10, but gains barely 1% per point after that, reaching 68% at level 20, then crawling to 76% by level 40. Some skills are so valuable that they're worth boosting even with diminishing returns, but this depends on the equipment, the play style, and the build.
Finally, only skill points spent in a skill count for the synergy bonuses, +skill equipment does not synergize, with the exception of summoned creatures like the Necromancer's Skeletons & Druid's Wolves who do get synergies from +skill equipment.
Skill Allocation
The various skills are located in tiers in Diablo II. Groups of skills become available at level 1, 6, 12, 18, 24, and 30. No points can be put into skills of a given tier until your character is at least that level, and once they reach that tier they can only put in one point per level. For instance, a character at level 14 could only have 3 points in a level 12 tier skill, and a character must reach level 49 before they can max out a level 30 tier skill.
It's common practice to save up skill points for skills coming at a higher tier, especially when there are two or more desirable skills at that tier. A character might choose to struggle along with just 1 point in a level 6 skill; saving their skill points until level 18, when they will start putting points into 2 different skills, thus using up two skill points per level up. Many character builds have 2 or 3 high quality skills at level 30, and are therefore quite weak in their 20s, as they struggle along using lower level skills and saving their points so they can invest them into 2 or 3 skills every level past 30, when they will become much stronger.
Skills from Items
It's possible to find equipment that boost your skill levels in various ways. Items can boost the level of an individual skill, a single skill tree, every skill on one character class, or every skill on every character class. These bonuses are of no use until an actual skill point has been placed in that skill, though. A character with +2 to all skills, +3 to a skill tree, +3 to an individual skill will get no benefit from that until they put a point into that skill, at which time they will immediately have level 9 in that skill. (There are a few exceptions, of course. See below.)
Items that grant skill bonuses are much valued, though their utility varies from character to character. A few of the most common bonuses are: grand charms with +1 to every skill tree in the game, and magical and rare items (gloves and amulets especially) can add skills to particular skill trees. Many better quality items, such as sets and uniques, have such bonuses as well.
Most classes have individual item types that can grant bonuses to individual skills. Normal, magical, and rare wands can have +1-3 to up to three individual Necromancer skills, as can Necromancer Totems (shields). The same is true (generally speaking) for Assassin Claws, Sorceress Orbs and staves, Paladin scepters, and Barbarian and Druid helms. Amazon weapons grant +1-3 to the appropriate skill tree, and only Paladin shields do not grant bonuses to skills or skill trees (they have inherent resistances or +damage/attack rating properties).
Item Grants Skill
Some special items grant individual skills before a character could normally use that skill. The usually come in the form of charges, such as amulets that allow teleportation, but only a certain number of times. Such items can be recharged at the NPC blacksmith, for a fee.
Other items are more generous, and grant the ability to use skills as many times as you wish, at no more cost than some mana. These items grant a skill to use just as if it were from your character's skill tree. These skills are referred to as "oskills," after their designation in the game code, and they are found almost exclusively on runewords. For example:
The Call to Arms, which can be made in any weapon, comes with three Barbarian skills:
- +1-6 To Battle Command
- +1-3 To Battle Orders
- +1-2 To Battle Cry
These skills can be used an unlimited number of times by any character who equips this item.
These type of bonuses are slightly capped for characters who own those skills naturally. In that case, the bonus can never be more than +3. So a Barbarian using Call to Arms might dual wield two weapons with the runeword in them, but he would not get more than +3 to Battle Orders from either of them, for a total of +6.
Skills on Hit/Death
Other items grant the use special skills, but only on hit, when hit, or upon death. Rainbow Facets, the unique jewels added in v1.10, are well-known examples, since most of them have a very high level spell that casts 100% of the time upon death.
Items that cast a spell some % of the time when your character is hit or when you hit a monster are more common. Many types of magic and rare armor can spawn with stats like "5% chance to cast Frost Nova when hit." These are usually a novelty, but can be helpful in some cases. The most useful are weapons that have a 5% chance to cast Amplify Damage, but even those are only useful in specialized cases.
The most popular use is for a Bowazon to have a bow on the weapon switch with the "of Amplify Damage" suffix. When facing a large mob, a Bowazon can land dozens of hits a second with Multishot, and that makes even the low 5% chance almost certain to trigger. The instant it does and the wide radius Amplify Damage is cast, the Bowazon switches to her usual bow and deals (approximately) double damage to every cursed monster.
Skill Synergies
Synergies were always in the game, but became much more important in the v1.10 patch. Synergies are skills that boost other skills or that are boosted by other skills. Synergies are only added by actual points in a given skill; various +skill equipment will add points to given skills, but those points will not count for the synergy bonuses.
Synergy relationships can be complicated and work in both directions.
For example, each point in the Paladin combat skill Sacrifice adds 12% damage to Zeal. Also, each point in Redemption adds +15% damage to Sacrifice, and each point in Fanaticism adds +5% Damage to Sacrifice. A character who wished to use Sacrifice as their main skill would therefore want to max it out, and also max out Fanaticism and Redemption, and at that point they might as well put a few points into Zeal, since the 20 points they'd sunk into Sacrifice would make Zeal quite effective. This character would do very high damage with Sacrifice, but note that they spent 60 skill points in the process, leaving very little for other skills.
Synergies should be looked over carefully before allotting your skill points -- in this instance points in Zeal only add 6% damage (they add 10% AR also), while points in Sacrifice add 12% damage to Zeal. So if your goal is to do high damage with Zeal, you should put in enough points to get 5 hits, and then work on maxing out Sacrifice, even if you never intend to use Sacrifice itself.
Many other skills work this way, encouraging or almost forcing a player to max out 2 or 3 or 4 skills in order to make just one of those skills work especially well. This feature of the game has proven somewhat controversial.
Synergy Pros and Cons
One the one hand, synergies they allow characters to specialize their skills and greatly improve the damage output of one skill or type of skill. On the other hand, this causes (forces?) characters to become very one-dimensional, with all of their skill points devoted to a single skill or skill tree.
For instance, most Sorceresses used skills from two or three trees prior to v1.10, with a major attack spell each from fire, cold, and lightning, or at least from two trees, to better deal with monsters that had high resistances or elemental immunities. Also, it was fun to pick between multiple skills and use them in overlapping fashion. In v1.10+ tri-elemental sorceresses are almost unheard of, since their character will do considerably less damage with her biggest skill in each tree than a synergy-specialized sorceress will with her one skill/tree. And since the hit points and resistances of monsters were boosted in v1.10, tri-elemental sorcs can't kill very effectively anymore, while new synergized mono-elemental sorcs are devastating to any monster not immune to their element, and helpless against any monster that is.
In effect, the synergies require specialized characters to play in mixed parties, while making other, more varied character builds ineffective. Player opinions differ widely as to whether this is a mark of progress, or a design failure.
