(This was written and relevant to 3.0 #6. Things may change in future updates...)

The Dominator soul, though not especially commonly used, offers the ability to virtually entirely shutdown certain souls whilst dealing moderate amounts of AoE damage. The damage is AoE fluff though, so is not very useful for actually killing people, but it can instead inflict devastation on many of the healing souls commonly seen in PvP. In addition to that, the vast majority of players do not know how to try and reduce the impact of the CCs it can apply.

In PvP, I feel the soul has more in common with some healing souls than it does with a DPS soul. It is a matter of picking the right ability to use at the time, rather than doing the same thing over and over in a loop, though there is some element of that in shutting people down with Arresting Presence.

Specs

I do not know a "best" spec for Dominator, if there is actually one. It is something that is likely down to personal preference, as your primary role is not to cause damage.

61 points are pretty much a necessity for getting the stronger abilities of the soul. The major attraction of Pain Armor is that it reduces the CD of Arresting Presence to 20s, giving it a mere 5s downtime - which can easily be covered by other CC abilities. I would not recommend running a spec without this, as it is simply too useful to pass up. Though taking Dominator as a subsoul could prove interesting, it isn't something I have any experience with, thus I will consider 61 point builds from here on.

It is then a question of choosing subsouls:
  • Arbiter: Aqueous blessing is nice for damage reduction, as you may get squirrel-marked and piled.
  • Archon: A few random buffs/debuffs. Nothing much to see here.
  • Chloromancer: The sheer number of hits provided by Void Wall and Lightning Wall proc veils a lot, but now with the healing nerf it's a bit pitiful. Natural intelligence is triggered by a lot of abilities. Entropic veil can be used on big CDs to boost damage noticeably.
  • Elementalist: Forget it.
  • Harbinger: Blade buffs add a tiny damage boost. 10% SP is nice.
  • Necromancer: Rather useless.
  • Pyromancer: First tier talents and early abilities are no help whatsoever. Internalize charge is the only thing that may be worth looking at.
  • Stormcaller: First tier talents are great. Crit chance in second tier is nice too, as is Ride the Wind for move speed and CC removal. Conductive medium may prove useful too, though how useful damage bonuses really are is questionable.
  • Warlock: Don't need any more charge, it's pretty much pointless.

Right now I run a Stormcaller/Arbiter based spec. Before 3.0 I used to use a Chloro one, but with the healing changes it hardly seems worthwhile now.

For masteries, pick up Arcanist's Shield; I have yet to experiment much with the others. There's nothing really made for Dominators in the other tiers, though.

Warfronts

Dominators are effective, but situational. Alone, they are more of an annoyance than a threat: you will almost certainly lose in any small battle. While it's possible to shut down an enemy, you don't possess the means to do the killing: that is the job of the ever-present pyromancers. That limits the warfronts they can be used in a bit:
  • Black Garden: Great for the Fang where everyone's together and there are healers to annoy. Less useful in domination where people tend to spread out, though if everyone's fighting over the middle it can still have a place.
  • Blighted Antechamber: When alone you can annoy people but nothing more. When fighting over flags or control points, there are plenty of potential targets. Otherwise, you're probably better of switching to something like pyro, if you don't mind switching to a spec with so few buttons.
  • The Codex: So long as you don't remain alone defending points, there is use for a Dominator here.
  • Ghar Station Eyn/Library of the Runemasters: Very effective for disrupting enemy healers, leaving the rune carriers to die on their own.
  • Port Scion: Not the best spec for running sourcestones, but if you end up at the bridge for some reason then you'll be useful.
  • Karthan Ridge: Another good map, there's usually targets for you without leaving you too exposed.
  • Whitefall: Same as Karthan Ridge really.

Conquest: The sheer amount of AoE burst damage that can be done by dominators made this worthwhile in the past, even if the CC didn't. Without knowing what 3.0 Conquest will bring there's no way of knowing what will happen, but if there's still the same battle scale then it will certainly be valuable.

Abilities

Dominator opens itself up to having a lot of buttons to use. Using macros to string abilities together doesn't really make logical sense as everything you have is situational. Knowing what to use isn't easy: knowing the inner workings of the spec your target is playing is a great advantage.

On your bar, you want:

Buffs:
  • Anything from your subsouls
  • Pain armor

Others (in no particular order):
  • ST spam macro
  • Transmogrify
  • Deny macro
  • Storm Shackle
  • Transference
  • Split Personality
  • Voltaic Feedback
  • Void Wall (Don't ever use a @gtae macro for this one!)
  • Haunting pain
  • Degeneration
  • Nyx's Orb macro if you like it, otherwise don't bother
  • Mass Exhaustion macro
  • Priest's Lament
  • Death's Edict
  • Break Free
  • Arresting Presence
  • Lightning Wall macro
  • Reflective Presence
  • Grasping Void macro
  • Mass Betrayal macro
  • Traitorous Influence
  • Malevolent Shield
  • Gravity Void macro
  • Mana Wrench
  • Mental Focus (You will probably never need this unless somebody's really trying very hard to starve your mana)
  • Reflective Command, if not putting it in a macro
  • Anything else from your subsouls that's worth using

Macros

Spoiler!


Remember, your first priority is not to kill the enemies. Leave that to the pyros that are everywhere now it's so stupidly easy to play.

Firstly, look for a victim. Healers are the obvious place to start. Use the scoreboard or an addon meter to get the names, and mark them. Use /tar with the first few letters of their name if you can't see them. With practice, it's quite possible to recognise healers by their movements and even their animations: CT spamming physicians somehow look different to any other player, for example. Choose your target wisely: a strong healer or powerful DPS are the most obvious options. Don't forget to make the most of marks for your targets.

What you do next is then very much down to what you've just selected. Your biggest shutdown tool is Arresting Presence, and as such I base my actions around a simple cycle of AP and a few other abilities. Some specs are more susceptible to it than others, though: it's not always worth the time to keep it up on somebody. There is no substitute to having at least tried to play the most common specs that you will want to target, preferably in PvP; as a brief guide I've categorised the main notable classes that I'm aware of below.

Vulnerable to Arresting Presence: these specs are seriously reliant on cast time abilities. Arresting Presence will seriously hinder their ability to do anything beyond popping the odd CD ability.
  • Sentinel - No invocations. The whole soul is built around cast time heal spells.
  • Chloromancer - To do any kind of noticeable healing outside CD abilities, they need to use cast time abilities.
These specs can partially carry out their role while under Arresting Presence, such as by avoiding the use of certain abilities:
  • Purifier - No wards. They can use symbols, and possess a cleanse-all which may remove AP even if covered (see below)
  • Warden - No cataract or mana regeneration channel. They can still heal, but their only no-CD instant AoE heal is a mana-munching one: if you mana starve them as well then they become useless as they can't channel to get their mana back.
  • Liberator - Various high power AoE heals have activation time. They can still heal, though.
  • Pyromancer - Without fireball, the spec runs into trouble when flame bolt is on CD. Also interrupts the two main CD burst abilities. Heat wave partially negates AP by reducing fireball's cast time so much.
  • Inquisitor - Interrupts CD burst abilities that hurt a lot, as well as preventing Bolt of
  • Physician - Interrupts Causal Treatment and Preemptive Therapy, as well as hitting Biofeedback if it's used. Not using the former is a HPS drop, and many players take some time to notice that they are being interrupted consistently.
  • Bard - Having Cadence or Cadenza interrupted constantly is a serious irritation as it throws the usual flow of the spec out the window.
  • Tactician - Means that torrents aren't really much of an option any more. (This severely hampers the AoE damage and healing of the spec, but doesn't remove it completely).
Notably, these are not hindered by Arresting Presence much, if at all:
  • Defiler - No cast time heals whatsoever.
  • Dominator - Very few cast time abilities, and can reduce cast times to below 1s to avoid the interrupts.
  • Harbinger
  • Shaman
  • Other warrior specs
  • Other rogue specs
Specs I lack any experience with that could be affected more significantly:
  • Elementalist
  • Marksman

I'm either uncertain about most other specs having not tried them myself, or the result of AP is "Meh", with it affecting one or two abilities at most.

When using Arresting Presence, try to always put Haunting Pain down immediately before you use AP. This is because of cleanse orders: the first debuff applied is the one cleansed first, meaning that your victim must first burn through a full thirteen stacks of Haunting Pain before they are able to use any cast time spells. Even if they move around and spam cleanses on themselves to get rid of HP as soon as it is applied, that is still time they could have spent healing, and if you add Priest's Lament then they will almost certainly be debilitated a few times by the time it is off them again.

It is worth noting, however, that Rogues have a cleanse-all in their War PA on a 1 min cooldown, and purifiers have a cleanse-all on a 20s cooldown. With that said, many people aren't aware of and won't deal with a covered AP even if these options are available to them, so it's worth a try anyway.

Now that your target is under AP, and it is covered, you then have the choice of what to do with the rest of your time. This is the part that is situation-dependent. Once AP wears off though, it's worth keeping some plan to stop them getting out cast time abilities in the 5s they have before AP is ready again: Death's Edict or Thunder Blast work nicely. Remember that you need to HP them before reapplying AP, too.
  1. Do more to your target. Virtually any ST ability you have is fair game, though keep in mind the 5s downtime of AP where TB or DE will come in handy.
    • Malevolent Shield is most useful to stop people being healed up at the last moment, like a DPS's burst. The heal blocking isn't high enough for much else, and even then it's a bit lackluster. Still, for an instant ability it's not bad, and the uncleansable effect is quite nice too.
    • Storm Shackle can stop your target running away. The damage is secondary, really: it's difficult to make the most of the AoE element.
    • Priest's Lament helps hinder their instant heals while AP stops any cast time abilities. I'd strongly recommend using this if they are a healer that isn't a purifier. With purifiers this is nice to stick on them after they've cleansed AP, assuming they reliably do use their cleanse-all, that is.
    • Traitorous influence does some AoE damage and adds mana pressure.
    • Transference is great for mana/energy pressure, but keep in mind that it's most useful when they aren't debilitated thanks to it's short duration. Try and avoid using this while they have AP's debilitate or Priest's Lament on.
    • Mana Wrench is only useful for mana/energy starvation. This is useful when harassing one healer isn't enough for your team to kill them: draining all their mana is a more effective means to shut down clerics/mages. When considering healers, it's most effective on Wardens. Less useful against rogues/warriors because of their low pools; physicians in particular can regenerate energy regularly without even needing a to use a GCD.
    • Degenerate: Serves as an annoyance rather than anything else. If people don't keep alerts on their buffs then it's worth exploiting.
    • Split Personality: These things do a modest amount of damage if they last their full duration, but it'll be painfully obvious that you are a Dominator and where you are when you use it.
    • Voltaic Feedback: Using this is often better than the spam macro if they don't have it on them already, but healers tend to trigger this slowly.
  2. Tab around and squirrel some people. High health percentage and not under attack are good criteria for it. It's also worth mentioning that using it on somebody also interrupts them, even if they take damage immediately after and it breaks the CC. This will however give them debilitate immunity as normal - use it sparingly! Don't forget to set your AP victim as your focus target so you can switch back afterwards, too.
  3. Use Deny. Your healer might not notice but deep down inside they will love you forever.
  4. Use Reflective Presence. Keep in mind that this eats your charge, which conflicts with Lightning Wall and (most importantly) AP. Watch the timing of this one, you don't want to be waiting to reapply AP.
  5. Use an AoE ability.
    • Mass Betrayal is the most powerful single ability against a clump of players, with a really long CD. Don't waste it, make sure that you're not running into a group of enemies alone. The best time to use it is when your targets are clumped up and fighting the rest of your team: that way they won't disperse too soon afterwards and there's some point in emptying everyone's mana bar.
    • Mass Exhaustion is effective once people clump up, though not if everyone's on low health. It's a fairly good opener if the enemies are all close together, but it does have a shorter range than your other abilities.
    • Gravity Void and Nyx's Orb are sort of filler abilities, handy when nothing better is available. CCing somebody before casting either will speed up the cast. Nyx's Orb appears to have no target limit, which is useful in some situations, particularly Conquest. Its terrible travel speed can make hitting targets interesting, though.
    • Grasping Void can help Mass Betrayal do some more damage. Without MP active, it's just another little irritation.
    • Lightning Wall and Void Wall are all about placement, and will make up a noticeable chunk of your total damage. Void wall is very unusual in that it hits only around the edges of the circle, which is why you should always target it yourself and never use a cast @gtae macro for it.


A few more miscellaneous notes:
  • As a general rule of thumb, melee classes proc Voltaic Feedback extremely often - multiple times a second usually. If there aren't any other good targets, then it's worth considering saving your CD abilities so you can have them when you want them and using puny spells on what's in front of you.
  • Transmogrify and Storm Shackle will stop targets flying using the Blighted Antechamber pads if you cast them once your victim has just started jumping.
  • NPCs don't have the debilitate immunity: When hit with Transmogrify, player pets will only be held for 7 seconds but have no immunity. NPCs are squirreled for the full duration. It's worth mentioning that Ithluk the Maimed in Port Scion is (oddly) not immune to it, and produces a rather fat looking squirrel once transformed.
  • Casting a CC before Haunting Pain will make it instant, so you can hit enemies which you need to jump to have LOS of. Handy for healers hiding up the rocks in Codex.

Learning

Like reactive healing, there aren't many ways to practice this without going into warfronts and giving it a go. If you just play in those good warfronts I highlighted above and keep one healer under AP while you slowly get used to having so many buttons, you'll be helpin your team more than they know. The healer in question may not necessarily drop dead immediately and indeed it might not feel like you're doing a great deal unless you have experienced the same treatment yourself at some point - then you will know what it is like. Remember that the scoreboard definitely doesn't apply to you: while your damage should stay reasonably high anyway, that is not what Dominators are there for.

I would strongly not advise macroing anything else together. There are situations where you want the control: either because of certain specs' abilities (like purifiers and their cleanse-all), or to avoid wasting abilities when the target will die etc. There are shortcuts you can take, but these will ultimately hurt your effectiveness. If you must use them to reduce the sheer number of buttons available to you, then by all means do so but keep in mind that in the longer term you will benefit from not doing so. Make the most of keybinds, you will need a lot to avoid using the mouse.

Alerts

Pain armor. You don't want to cast AP without it.

Tracking AP's cooldown and time remaining on the target is useful, too.

>85% health tracker for transmogrify.

If you have difficulty using up all your abilities, alerts can be useful in knowing at a glance what's off cooldown. With so many buttons it can be difficult to know what is available to use.


Defending against Dominators
There are a number of things anyone can take away with them that can help them defend against the various abilities of the Dominator, especially if they enjoy healing.
  • Know what they can do to you, and what (if anything) your spec can do to get around it.
  • Watch the effects monitor, or set alerts for various abilities, notably Arresting Presence and Priest's Lament. If not covered, cleanse them off yourself as soon as possible, otherwise avoid cast time spells as much as possible when under Arresting Presence.
  • Spread out. Mass betrayal is a significant threat to any bunched up team, and can quickly starve the healers of mana/power so that they are unable to do anything while the entire team takes massive damage.
  • Mark them. A dominator has to keep reapplying their debuffs to stay alive. Getting rid of them as a priority after the healers will help keep your own team's healers happy. The squirrel is kind of appropriate for them, I suppose.

Hopefully this is of some use to people. I readily welcome constructive criticism, as well as any pointers as to what I have omitted as I'm sure I have forgotten a few things.