Class Mechanics

1. It is known that Sorceress's Spells will have different effects based on their elements: 
   • Some Lightning Spells will have a special mechanic called "Crackling Energy" that will make them leave behind orbs of energy. These orbs will be collectible and will restore some of Sorceress's Mana on pickup. This will basically serve as a sustain/utility tool but might have other synergies as well if the right talents are chosen. 
   • Cold Spells will offer a stacking slow effect, similar to the one known from the earlier iterations of Diablo. Hitting a target with enough Cold Spells will eventually stack the slow effect up to 100% and the target will become frozen for the remaining duration. We can already see that this will synergize extremely well with Spells that deal multiple hits and with Cast Speed modifiers. 
   • Fire Spells will have a high chance of setting an enemy on fire, just like they should. This will be similar to the ignite effect, known from other RPGs, and will provide additional effects if the right talents are chosen. 
2. Sorceress's main Class Mechanic is known as the Enchantment System. With it, Sorceress will be able to turn any of her Active Abilities (so, passives cannot be used in this system) into passive or semi-passive effects related to the selected skill. The selected skill will be disabled in the process. Known Enchantment Effects include: 
   • Periodic Automatic Meteor Casts on a random nearby enemy. 
   • Crackling Energy effect being replaced with conjuring Ball Lightning. 

Class Mechanics

1. Rogue will be able to alternate between Melee Weapons (her white weapons of choice are Swords and Daggers) and Ranged Weapons (Crossbows and Bows, possibly Javelins). Picking a specific weapon won't lock the Rogue out of using other weapon types and the Skill's stats will be calculated based on the appropriate weapons' stats (so, Ranged Weapons will be used for ranged skill calculations, etc.). As it currently stands, Diablo IV's Rogue is an amalgamation of the features known from multiple Classes featured in the game's earlier iterations (Demon Hunter, D1 Rogue, Assassin, and Amazon). 
2. Rogue is known to have three different Talent Specializations that will be unlocked by Class Quests: 
   • Shadow Realm - "Become Immune for 1 second, and pull target enemies into the Shadow Realm with you for 5 seconds. In Shadow Realm, you become stealthed, unstoppable, and deal 50% more damage to the afflicted enemies". This will have a 10s Cooldown. 
   • Exploit Weakness - "You can exploit the weakness in certain enemy attacks. All hits against these enemies become critical strikes and deal 60% increased damage". This is a passive effect. 
   • Combo Points - "Your Basic attacks now add Combo Points. Certain skills consume combo points for additional effects". This is a system similar to the one used by D2's Assassin. Combo points will stack up to 3 and using a Spender will expend all of them. 
3. Rogue will have access to a special Imbuing System that will let her modify the damage type of her skills and add various secondary effects. Available Imbuements are Shadow, Poison, and Cold, and the secondary effect will correspond with them: 
   • Rogues can lace their weapons with cursed oils, causing them to deal Shadow damage. Enemies damaged with weapons coated with such oils become Cursed. Cursed enemies that die will explode, inflicting a large amount of damage to all nearby targets. 
   • Weapons Imbued with Cold will slow enemies on hit and eventually freeze them in place. This mechanic will work just like the Sorceress's Chill effect. 
   • Poisoned Weapons will most likely deal Damage over Time and reduce the target's statistics in various ways. 

Class Mechanics

1. Necromancer will utilize various Curses that will afflict His enemies with various debuffs. This system is perfectly known to all Diablo veterans. Expect some of the Classics to return; Iron Maiden and Decrepify were already confirmed. 
2. Necro will have two resources at his disposal. These resources will be required to cast some of His spells: 
   • Corpses - Well, we all know where these come from. These will be needed to cast reanimation spells, for example (and corpse explosion, should it make a return). 
   • Essence - A slow-regenerating resource that can also be gained by using basic skills. This will be used to empower Bone Spells, among other things.
3. There will be four different playstyles available to a Necromancer, offering different strengths, weaknesses, and difficulties: 
   • Summoner - This will be the classic Necromancer based on reanimated undead minions and golems. However, its playstyle will be revamped and its biggest problems will be addressed. For example, Skill choices will be more flexible as minions will be sturdier and less reliant on certain talents. Thanks to this, Summon-based necromancers will be able to employ Bone, Blood, and Shadow magic as well. 
   • Blood - Blood Skills will benefit from large health pools and will be able to affect multiple enemies at a time (we imagine something like the Blood Boil Skill used by WoW's Death Knight). The more enemies a Blood Spell affects, the more powerful it becomes. Blood magic will also restore Necromancer's health and will allow him to escape danger. This archetype will be AoE-based and quite aggressive, thanks to life leech mechanics. 
   • Darkness - Dark Spells will replace Poison-based spells known from the previous iterations of Diablo. They will either deal damage over time or attack multiple times in a short window. They were also confirmed to induce Crowd Control effects and debuffs. One of the confirmed Darkness spells will create Corpses and restore Essence, so it is a safe bet to assume that Darkness Spells will work well with the Summoner archetype. 
   • Bone - This is the archetype that will appeal to players who prefer the direct approach to combat. Diablo IV's Bone Spells will be quite similar to their previous iterations, but they will now also be supplemented with additional effects (like Critical Strike) and will benefit from a large Essence pool. Bone Necromancer will also be a master of Crowd Control, thanks to spells like Bone Prison. 
4. Necromancer's Class-Specific Mechanic is known as the "Book of the Dead". It will allow the player to customize His/Her undead minions, choose how the minions will be deployed, which minions will be available, and how will they behave. There will be three core summons: Skeleton Mage, Skeleton Warrior, and the Golem, all of them will have three different variants, and each variant will have three modifications to choose from. This will create a lot of customization options. 

Class Mechanics

1. Druid's well-known-and-loved Shapeshift forms return in Diablo IV for everyone's enjoyment! Each form will have a different set of skills and abilities so that they will feel more unique than ever. Bear will be a slower but much tankier beast while the Werewolf will be an attack speed demon with a range of devastating melee attacks. 
   • There won't be skills that exist purely to transform Druid into His shapeshift forms. Instead, each skill can be cast while in a specific form (sometimes two forms, but never all of them). Using said skill will cause Druid to shapeshift automatically before the cast without any extra action. Once shapeshifted, the will Druid remain in that form for 3 seconds or until a different action forces them to shapeshift again. 
2. Druid's Earth-based Skills will have a chance to deal Crushing Blows, reducing the enemy Life by a percentage of their maximum health. This effect will be reduced against Players and Bosses, but it still will be extremely powerful. Think of it as a Druid's version of Static Field. 
3. Some of Druid's skills will have a chance to apply the Vulnerable debuff, which is an inversion of the Fortified buff. Vulnerable enemies will receive 30% additional Damage from attacks. This debuff is said to last until the afflicted enemy loses a specified amount of life from any source. It won't expire by itself nor will be overridden by Vulnerable debuffs from other sources. This mechanic will promote the use of multiple Skills, especially in shapeshift forms. It will also work well in Elemental/Shapeshifting hybrid builds. 

Class Mechanics

1. Barbarian's Arsenal system will allow Him to freely swap between different weapon types; from Two-Handed Maces to handy Shwort Swords or Hand Axes - Barb will have the right tool for any given situation. 
   • You will be able to possess two Two-Handed and two One-Handed weapons in your Arsenal and all Affixes from the chosen Weapons will apply all at once! However, just one Two-Hander or two One-Handers at a time can be used to perform attacks. 
   • Barbarian will have the ability to swap between His weapons dynamically at any time and assign specific Skills to different weapons. This way, you'll be able to always make the most out of your tools! 
   • Some of the Barbarian's Skills will require a specific Weapon Type to be used. This feature will work well with the Arsenal system. 
     • Skills may require a weapon to be bludgeoning (Maces meet this requirement) or Slashing (Swords, for example). 
     • Several Skills will require Two-Handed Weapons or Dual Wielding to be used. 
     • Using a Skill with weapon requirements will automatically swap to the best fitting weapon from your Arsenal. 
2. Barbarian will have a range of powerful utility skills at His disposal. These will include Crowd Control immunity, bonuses to health, and other useful things similar to boons provided by Barbarian's Shouts in Diablo 2 and 3. 
3. Barbarian will deal mostly Physical Damage, but He will have access to two distinct Specialization - Red (Warlord) and Orange (berserker). 
   • Warlord Skills are more defensively-focused and offer various party bonuses, survivability boosts, bleeding effects, opportunity strikes, and some Crowd Control effects. 
   • Berserker Skills are all about the offense and completely disregards Barbarian's safety. They will offer tremendous damage output, self-buffs, and speed, but won't provide any defense (on the contrary; they can hinder Barb's defense to some extent). 

END NOTE

Please remember that Diablo IV has not been released yet and thus all the information contained within this article is subject to change. We will update it as soon as new info becomes available. If you've found this guide useful and informative, don't hesitate to leave a comment below, it will motivate us to continue our work. If we've missed a piece of information that is important to you, please let us know! Also, please do note that this is an early version of our guide, and we will be happy to receive constructive criticism, that will help us improve it, so leave your suggestions in the comments section below.