Can anyone break down the mechanics of channeled skills.

Issue 1.
Specifically how often the "channel" cost is payed.
As far as I can tell most people running TR monks (for example) try not to get high attack speed.
So is the channel cost payed every attack? The higher your attack speed, the more you pay?
But the effect is not attack based. The effect is continued until you stop repaying the channel cost. (i.e stop attacking)

So in short, high attack speed gives you no advantage, but cost you more resources. That about right?

Issue 2.
Firebats is a chanelled skill, but Visage of Giyua has reduced cost Firebats. Is this reduction for the initial cost only, or for the channel cost as well?

@Bort

Issue 1 is correct. Attack speed directly affects cast speed, and will have you consuming more resources faster.

Attack speed does increase your damage, but if your main attack requires a resource and you do no damage or far less damage while it's down, then your effective DPS goes down. High CC and CD if that skill procs those is a much better option. (Skills like Sentry for a DH don't crit.)

Also, and not asked here, I know when my DH casts Gloom, Rapid Fire takes a snapshot, so I get the life steal until I finish channeling, or get knocked back, even after Gloom wears off. Strafe does the same thing.

I am unsure about the reduced cost gear, but am very interested in the answer. Hadn't thought of that.

@Bort

Visage of Guya reduces the channeling cost. I'm not sure about the initial cost, but reducing the initial costs from 222 to 212 wouldn't be noticeable, anyway.

I don't know if the channel cost is exactly aps, but I think it is. If the channeling cost is listed as 66 mana, I believe that's 66 mana per aps. If you're at 2.0 aps, you're paying 132 mana / second to use the skill.

The usefulness of aps in channeling skills aren't universal. When using Whirlwind, for instance, high aps means more frequent procs on Battle Rage and LoH so minimizing your aps isn't helping you there.

There are two ways to use Strafe, one of which @nuhertz covered which has to do with locking in the Gloom bonus at the beginning of the Strafe where it is advantageous for the hero to keep Strafe up consistently and means a lower aps is desirable. The other way to use it is to take advantage of the autoaim aspect of it to clean up stragglers without deviating from your walking path. Since there's no initial cost for Strafe, a higher aps simply means more bolts flying in a shorter period of time so aps is neutral, at worst.

Tempest Rush has a fairly sizeable starting cost relative to its channeling cost so there's an advantage to keeping it up. Most Monks use Tempest Rush for its increased movement speed so low aps is necessary to maximize the benefit of the skill. Notably, the auras use displayed dps which is affected by aps, but deals damage at a constant rate so aps only increases the magnitude of the damage caused, not the frequency at which the damage is caused.

I haven't played with Firebats, but the initial cost is so high compared to the channeling cost that a slow aps is likely the most efficient.

The rate of damage being dealt is unique to each skill. This is most relevant to CM Wizards with how often Wicked Wind can proc Critical Mass. S2W Barbarians also have breakpoints for their tornadoes and Whirlwinds and I suspect they exist for Rapid Fire DHs, but I stopped playing before I looked into that more closely. So technically you pay channeling cost per 'attack' rather than per second or per tick for whatever that tick-per-channeled attack is.

Hooray D3 mechanics!

Ok. Some feedback.

Got myself a -10 Mara and -9 SOJ.

I also used the following passives:

Blood Ritual (a very undervalued passive if you ask me)
Spiritual Attunement

Other stats (as read from my sheet) including the passives were:
DPS (only 40k, this was tested on my life/s WD with only the amulet and ring swapped out)
HP 43k
Mana 1198
Life/s 5144
Mana/s 76.94
Att/s 1.51

Was able to keep firebats up basically permanent.

Tried with the following as my 3rd passive:
Fierce Loyalty (Pets stay alive with life/s)
Grave Injustice (Doesn't really add much. Life and Mana pools fill up quite fast)
Spirit Vessel (For HC )
Pierce the Veil (more DPS)

With Pierce the Veil my mana pool emties, but after about 30s only.
(Without the -resource cost equipment it takes about 13s. So they definitely reduce the channel cost, like @ecocd said)

Problems with this build:
Major issue was that I can't move while casting. So I start the cast, and then have to stand there and hope stuff comes to me.

Things I liked:
Well... as you guys should know from all my other posts, I like the -resource skills. And this one was also fun, and didn't require 4 -resource pieces. Because I can still get a skull grasp and a voodoo mask to reduce even further. But I don't really see the point. But it gives you much better DPS options than some of the other reduced cost skills.

I see some potential for the Cloud of Bats or Plague Bats runes, that does more damage after a while. Because I channel forever I can get to the max, and keep it there. Basically thinking of Uber fights here.

More feedback.

Changed my Last Breath and Thing of the Deep for a Skorn.

DPS: 67K
HP: 38K
Mana: 1198
Life/s 4096
Mana/s 76.94
Att/s 1.08

With the slower attack speed I was able to keep up all time even with Pierce the Veil.

Not being able to move still sucked. And I didn't use vampire bats, so had no lifesteal. Just the life regen, which just isn't enough to keep you alive.

Check out my ScornDoctor. I use the same gear for COB and for Plague bats which I play more often now I've picked up another piece of gear with PUR.

I mostly play COB when solo'ing or playing in a group that has a monk that can pull.

Use Locust Swam -> Pestilence. You should be able to round up 1/4 of fields of misery or more by running ahead of the mob and casting on new mobs you find and the ones behind you. Then choose a spot and start channelling and then spam Spiritwalk/Soul Harvest/BidBadVoodoo and either Hex or Confusion.
Stuff just dies.

Read up here on COB "tick rates" and how IAS effects the channelling.

I love the build!