Resource

A Resource Pool is part of a character's ability to use Skills. It's generally gathered in various ways and expended upon using as skill, where skills have different "costs", and use a different amount of resource from the pool. Mana is the prime example of a resource pool.

Each character uses a different and unique resource in Diablo III:

The Barbarian uses Fury.
The Demon Hunter's resource is under development.
The Monk uses Spirit.
The Witch Doctor uses mana.
The Wizard uses Arcane Power.

Diablo Games

In Diablo I and Diablo II all classes used Mana as their one main resource, but in Diablo III not all classes share the same resource. In all the Diablo Games so far, the resource pool is located in the UI, on the bottom right hand side, usually in an orb or sphere.

Item Bonuses

The issue of items providing bonuses to resources is complicated in Diablo III since there are so many different resources. In Diablo II +mana was a simple bonus of use to everyone (though not equally useful). But in Diablo III only the Barbarian benefits from Fury, only the Monk from Spirit, etc. And the bonuses to each resource vary; for some increasing the total pool is viable, for others only improving the fill rate, or decreasing the drain rate. This prevents the team from using some sort of universal "+resource" modifier, and requires a lot of individual item bonus tweaking.

Jay Wilson answered a question about this during an interview from Blizzcon 2010.[1]

Jay Wilson: Yes we’re definitely going to put in objects that will do that. It’s been a question of how we want to implement that. Right now every class has their own resource. And that’s the goal. If we can’t get that to work, if we can’t make them different and all working adequately, then we might double up on some resources on some characters. We’ve waited to do the itemization until we have the resources locked down. If they’re that different then we might restrict the resource bonuses to class-based items.

It feels pretty bad when you get say, a sword that’s got… it’s one thing to get a sword with say, plus strength on it, and you decide not to use it because that bonus isn’t really the best for your Wizard. That’s one thing. But if you get a sword that has a resource bonus for another class, that’s entirely unusable for you, that’s no fun. That feels worse than just getting a stat that’s questionably not for you. Having an object that you can equip that states in it a bonus that’s useless to you, that feels bad.

We do have class-based items for that. We’re also doing a lot with enchantments, because enchantments don’t feel bad if you find an enchantment that’s not for you, the way an item is.

Diablo III Resource Pools

Fury

Fury, abandoned "traffic light" form.

Fury is the resource pool for the Barbarian in Diablo III, although he used to rely on mana in Diablo II. Fury shares several similarities to the World of Warcraft Warrior class' "Rage" resource in that it generates through damage taken and dealt and decays over time when out of combat, although the details between the two differs.

Generated by:
- Dealing damage
- Taking damage

Removed by:
- Using abilities that requires Fury, generally more powerful abilities.
- Inactivity over time.
- Unknown if some creatures can leech it.

Fury Related Skills:
- War Cry generates a certain amount of Fury and increases armor.

Arcane Power

Arcane Power is the new resource for the Wizard class, allowing the wizard to cast her spells without running out of the resource any time soon. It is a flat amount of resource, that cannot be increased by items or stats (but maybe by skills) and regenerates really fast. It is akin to World of Warcraft's Rogue resource, which is Energy.

Restored by:
- Regenerating
Removed by:
- Using an Ability.
Arcane Power Related Skills:
- N/A

Mana

Mana is the most known resource pool, having been in many RPGs and is usually represented by a blue colour. The Witch Doctor is the only class to use mana as his ability resource in Diablo III.

Restored by:
- Picking up Health Globes (with a specific skill)
- Regeneration
- Killing enemies with specific skills
Removed by:
- Some creatures leeching mana.
- Using an Ability.
Mana Related Skill(s):
- Witch Doctor's Soul Harvest: Killing Enemies with this AoE Spell will restore the Witch Doctor's Mana.
- The Wizard's Mana Recovery increased the chance of a Mana Globes dropping, but was removed.

Spirit

Spirit is a recently revealed resource that the Monk uses. It is restored by using combo skills, like Way of the Hundred Fists which do not really cost anything, and can be used for his signature skills, such as Impenetrable Defense and Seven Sided Strike.

Restored by:
- Using Combo Skills
Removed by:
- Using a Signature Ability.
Spirit Related Skills:
- N/A

Unknown

The newly-revealed Demon Hunter used mana at Blizzcon 2010, but that was only as a place holder. The developers refused to give out any hints about what sort of resource the class might use long term.[2]

Question: Any clue about the resource for the Demon Hunter?

Jay Wilson: If I knew I would give you a clue. We decided not to worry about her resource until after Blizzcon.

Development

All of the classes debuted with some form of Mana for their resource. Their permanent resources were added in during later development, and tinkered with extensively.

Barbarian

Fury is the Barbarian's resource. It builds up as the Barbarian takes or deals damage, and is expended on most of his attack and buff skills.

Fury debuted at BlizzCon 2008, in the form of a globe. During later development it changed into a "traffic light" stack of three orbs at Blizzcon 2009, before changing back to a full globe in early 2010. Many more details can be seen on the Fury article.

Monk

Spirit is the Monk's resource. It's built up by dealing damage with combo skills and expended to cast other, non-combo skills. It was described in mid-2010, and debuted at Blizzcon 2010 in October of that year.

Witch Doctor

Mana is the Witch Doctor's resource. It works much as Mana did in Diablo I and Diablo II; some amount is expended with each cast spell from a pool that regenerates over time. Various skills and items can hasten the regeneration rate, and the Witch Doctor can also gain mana from health orbs if he has invested in the skills and traits that allow him to do so.

The Witch Doctor may ultimately get a different resource; it would work like mana, but would have a different name and a slimy, gloopy greenish appearance, simply to make it seem more Witch Doctor themed.

Wizard

Arcane Power is the Wizard's resource, though the D3 team said, in late 2010, that it might switch back to mana, since they're not entirely satisfied with how the resource works. Prior to Arcane Power, the Wizard used Instability, which was scrapped since it did not make the character feel "glass cannon-y" enough.

Demon Hunter

The Demon Hunter class used mana when she debuted at BlizzCon 2010. This was a place holder, but the team was not ready to give any hints as to what her final resource might be.

Reference