I have recently embarked on a mission to evaluate some of the skills that can have its resource cost reduced by items.

In short Mara's Kaleidoscope, Stone of Jordan and Skull Grasp can each reduce the cost of certain skills. And all 3 items have the same list and the skill reduction stacks.

Furthermore it seems that each skill on the list has at least one other item type that can reduce its cost even further. I didn't specifically search for the fourth item for all of them yet.
I have found some that can be on a shield OR a 2h weapon, but I haven't found one that can be on 5 items that you can equip simultaneously yet. It also seems that the maximum reduction on other items are the same as on SOJ and Mara.

The skills are as follows: (Showing the Max reduction on the 3 items, and on which other item it may occur)

. . . . . . . . . . . Original cost . . . SOJ Red . . . Mara's Red . . . SkullG Red . . . Other
Demon Hunter
Chakram . . . . . . . 10 . . . . . . . -5. . . . . . . . -5 . . . . . . . . . . . -4 . . . . . . . . . . DH Chest
Impale . . . . . . . . .25 . . . . . . . -5. . . . . . . . -5 . . . . . . . . . . . -4 . . . . . . . . . . ?
Cluster Arrow . . . 50 . . . . . . . -5. . . . . . . .-5 . . . . . . . . . . . -4 . . . . . . . . . . ?

Witch Doctor
Firebomb. . . . . . . 10 . . . . . . . -8. . . . . . . . -8 . . . . . . . . . . . -7 . . . . . . . . . . Ceremonial Knife
Zombie Charger . 140 . . . . . . -10. . . . . . . -10 . . . . . . . . . . -9 . . . . . . . . . . ?
Firebats . . . . . . . . 98 . . . . . . -10. . . . . . . -10 . . . . . . . . . . -9 . . . . . . . . . . Voodoo Mask

Monk
Cyclone Strike . . . .50 . . . . . . . -5. . . . . . . .-5 . . . . . . . . . . . -4 . . . . . . . . . . Spirit Stone
Lashing Tail Kick . . 30 . . . . . . . -5. . . . . . . .-5 . . . . . . . . . . . -4 . . . . . . . . . . Daibo

Wizard
Meteor* . . . . . . . . 50 . . . . . . . -5. . . . . . . .-5 . . . . . . . . . . . -4 . . . . . . . . . . Orb
Hydra . . . . . . . . . . 15 . . . . . . . -9. . . . . . . .-9 . . . . . . . . . . . -8 . . . . . . . . . . Wizard Hat
Arcane Torrent . . . 16 . . . . . . . -5. . . . . . . .-5 . . . . . . . . . . . -4 . . . . . . . . . . Wizard Hat
Disintegrate . . . . . 18 . . . . . . . -5. . . . . . . .-5 . . . . . . . . . . . -4 . . . . . . . . . . Wizard Hat

Barb
Weapon Throw . . . 10 . . . . . . . -5. . . . . . . .-5 . . . . . . . . . . . -4 . . . . . . . . . . Mighty Belt
Rend . . . . . . . . . . . 20 . . . . . . . -5. . . . . . . .-5 . . . . . . . . . . . -4 . . . . . . . . . . Mighty Belt
Hammer of the A . . 20 . . . . . . . -5. . . . . . . .-5 . . . . . . . . . . . -4 . . . . . . . . . . 2H Mighty Weapon, 2H Axe, Shield

So in short the following skills can be reduced to 0
DH - Chakram
WD - Firebomb
Wiz - Hydra
Wiz - Arcane Torrent
Wiz - Disintegrate
Barb - Weapon Throw

The following can get quite close to 0
Barb - Rend
Barb - Hammer of the Ancients


I have tried the following.
DH - Chakram
Currently running a DH with -5 SOJ and -5 Natalya chest. I don't have any Hatred generating skills, and I use Chakram as my primary attack. Still needs some more play, but seems a fun alternative for now.

WD - Firebombs
Well, actually I didn't even get around to buying resource reduction items. I just saw that my WD mana regen is so high that I can spam this spell all the time anyways, and I didn't enjoy the spell at all.

Wiz - Meteor
With the starfall rune meteor cost goes down to 35. So after reduction of (-5 SOJ, -5 Mara, -4 Skull Grasp and -5 Orb) it is 16. I also have 3 items that gives arcane power on crit. So I gain 28 arcane power per crit. So in theory if every second meteor gets one crit I get my mana back. (More or less)
The main problem I had with this one is the delay between casting and the meteor dropping. I would spam meteor a couple of times, but then the first couple would kill the mobs, and the rest falls on empty ground, and is thus unable to crit and get my Arcane power back.
I still want to try this one out with the Meteor Shower rune. The total cost is then still 31 mana, but a larger area is covered and hence more possible crits.
Obviously this should also work nice with Critical mass to keep other spells up.

Wiz - Arance Torrent
I dislike this spell so much that even getting it for free felt like a waste of resources. I tried most of the runes and simply couldn't find one I enjoyed spamming.

Barb - Hammer of the Ancients
This one is by far the most fun. See my notes over on here on barb pages.



I might still give Impale a try. It can't go down to 0, but a hatred cost of 6 might be low enough to feel you can spam it anytime.

I still want to give Disintegrate a go. My wizard knowledge is very low, so I'm not even certain if this is a channel spell, and if the channel cost is also reduced, or just the initial cast.


Rend can go to close zero but since the rend effect can't be applied multiple times at once its not really a good primary attack, so not really worth reducing. At least not giving up valuable ring and amulet slots to do so.

And weapon throw only requires 2 items to get it down to 0, so it might be a fun range Barb build.



All in all it can be quite fun, but you have to live with giving up Amulet and Ring slots, and this hurts.
SOJ can't have stats or CC. So many people see this as bad.
And finding Skull Grasp and/or Mara with the correct skill reduction along with high CC is very rare and expensive.

Searching for these SOJ, Mara and Skull Grasp on the AH is very painfull, since you can't filter for the appropriate skill.

I have learned a new trick thanks to @nuhertz that works for SOJ at least.
Don't type in Stone of Jordan in the Unique item name.
Simply select all Armour types, and then you will be able to select
Damage VS. Elites
and Max (resource)
Resource being whatever it is for the class you are interested in. (Fury, Discipline, Mana, etc)

This at least filters out all the non-class SOJ's. And trust me, this makes a massive difference.


For Skull Grasp and Mara I'm trying to find ones with CC, so I normally put that in which reduces the number of hits drastically. Unfortunately the price goes up with CC also.

IIRC there was a discussion on reddit or blizz forums for the reduced resource cost. And a statement (don't remember if tested or not) was that any spell at least has a cost of 1 resource.

Did you test it yourself and have some insight on this @Bort ?

I have tested the ones mentioned.
But TBH I can't really say if it costs 0 or 1.
What I can say is that for example with Chakram.
(Original cost 10, 2x -5 cost items) I don't see my hatred amount moving.
But that can just mean that my Hatred generation is more than enough to keep up with the 1 cost.

I will go and confirm this over the weekend.

Posted by Bort at 03/14/2013 10:57 PM

I might still give Impale a try. It can't go down to 0, but a hatred cost of 6 might be low enough to feel you can spam it anytime.

You could drop that six for Impale even further by using the Bat Companion (bonus 3 hatred) & Templar w/ Inspire (bonus 1 hatred regeneration)... :-)

@h3110

Ok, it seems that the spells do cost at least 1.
If I cast the Chakram I have a split second that I can see my hatred drop by one, then it refills.
I tried with 2H crossbow, 2x 1h crossbow and 1h crossbow + quiver.
All combinations my hatred regenerated fast enough so it "looks" like the spell is 0 resource cost.

Wow @Bort lots of effort you put in verification.
My intention was more to let you know that there might be no resource reduction for free cast.
Who cares if its 1 or 0 if regen is higher ;-)

Good Thread to get an oversight of the reduced cost spells, thanks @ Bort.
I´d like to add, that the WD also has Zombie Dogs and their cooldown can also be reduced to zero.
Heres how it works:
Basic CD is 45 seconds. Let´s add the Tribal Rites passive for -25%.
reduction, which is 11,25 secs, that equals 33,75 secs.
A Helmet can reduce for 9 Seconds max, then you put on a Homunculus Mojo, its reduction varies btw. 10 and 20 Seconds, a Homu with 19 secs is already affordable. You then only need one Soj/Maras/Skullclamp with 5 or 6 secs reduction, depending on you getting a 19s or 20s Mojo. Happy Sacrificing :)

gabhh

@gabhh.

Thanks for the update. I did actually look into Zombie dogs, but I missed Homunculus, so I thought the best you could do was 17s cooldown.
With homunculus added it's actually real easy to get to 0 zombie dog cooldown.
I also missed Tribal Rites, but you can do it without Tribal Rights.

Starting cost 49. (According to the blizz website, will confirm if it's actually 45 like you mention)
SOJ and Mara -8 each.
Skull Grasp -7.
Homonculus -20
Visage of Giya (or other voodoo masks possibly) -9
Tribal rights -12
Total reduction: 64. So you can easily make it just with the items, or with 4 items and passive.
Or even with: Passive + Mara OR SOJ + VoodooMask + Homonculus. So you don't have to give up all those valuable ring and amulet slots.


Zombie dogs is also the first skill I find that can be reduced by 5 items at once.
There might be more, I just don't know about them.

Posted by gabhh at 03/19/2013 08:35 AM

then you put on a Homunculus Mojo, its reduction varies btw. 10 and 20 Seconds, a Homu with 19 secs is already affordable.

The cheapest on bid right now is 183 million Gold. I'm not sure that's most people's definition of "affordable." It ain't mine.
Edit: other prices with bids on them under 3 hours:
SoJ -4 reduce Zombie Dogs, 21% BvE - 5 million
SoJ -6 ZD, 24% BvE - 25 mil
SoJ -7 ZD, 27% BvE - 168 mil

Skullgrasp -5 ZD - 20 mil
Skullgrasp -6 ZD, 45% AR - 30 mil

It's still a build for people willing to put 20 USD into the game, but you are right that it's substantially cheaper than it was a month ago.

That´s a clear case of not checking the AH before posting. Last time I checked gold prices on homunculus, the ones with 19s CD were around 15 million. Old information as it seems - sorry for that.

Posted by gabhh at 03/21/2013 01:03 AM

That´s a clear case of not checking the AH before posting. Last time I checked gold prices on homunculus, the ones with 19s CD were around 15 million. Old information as it seems - sorry for that.

Wow, do you have any you're willing to sell? ;-)

That makes me think there's one or two people that saw an opportunity and bought up every single one available to corner the market.