Playstyle & Rotation
Garrote has a 5.2 pandemic timer, meaning that refreshing it when its at or below 5.2 seconds left on its duration is preferable. It's worth noting that in most cases, Garrote's cd comes up before that mark, so using it instantly can prove to be a slight dps loss in some cases, but it certainly helps with the fluidity of the spec.
Rupture on the other hand, has a 7.2 second pandemic timer, meaning at 7.2 seconds or less, you're free to refresh it. It's important to follow that rule outside of Vendetta and/or Kingsbane as it helps a lot with the rest of the gameplay. Remember that since patch 7.1.5, each Rupture tick deals the same amount of damage regardless of the combo points used.
Opener with Mantle of the Master Assassin and Nightstalker
- Potion of the Old War
- Draught of Souls (If equipped)
Opener without Mantle of the Master Assassin using Nightstalker
- Potion of the Old War
- Mutilate to 5 combo points
Without Mantle of the Master Assassin it's very close. If Heroism/Bloodlust is present on the pull, I'd advise Potion of the Old War on your opener, and Prolonged during the fight. If lust is not present, double prolonged.
If you aren't specced into Agonizing Poison, you want to track your Envenom uptime to maximize your Deadly Poison procs as it's a significant part of your damage. If you're specced into Agonizing Poison on the other hand, Envenom's uptime is only relevant during your Kingsbane duration.
Maximizing the potential of your Surge of Toxins is a major part of the spec. Before Surge of Toxins runs out, you always want to clip it, as in using your Envenoms right before it expires to get the full benefit of the buff. You don't need to clip it with Rupture, however.
If you see that you're starting to fall behind, and you can no longer use Envenoms during Surge of Toxins, you should pool your energy, preferably with 4/5cp on your target, and then Envenom to get into a decent rhythm again. The reason why you want to have combo points on your target is that right as you Envenom without Surge of Toxins, the next Mutilates to come are buffed by your Surge of Toxins, along with your next Envenom.
Before using your Vendetta, you always want to drain your energy bar in order to get the most out of its refill. If you're using Duskwalker's Footpads, you want to make sure that you drain your energy before your Vendetta becomes usable, as you don't want to be using any energy with Vendetta available.
Before using your Kingsbane, you want to try and refresh your Garrote and Rupture on the target if they're about to fall off and below their pandemic marks thus allowing you to push out Envenom's to increase the potency of your Kingsbane.
It's important to understand that your Envenom is your highest hitting ability that does direct damage to the boss. As such, during your Vendetta or Old War you want to maximize the amount of Envenoms you push out. To do so, you must be mindful of your dots, refreshing them before Vendetta becomes available as you don't want to be refreshing them multiple times during its duration. It's critical, however, that you do not Envenom if your Garrote and/or Rupture is not up on the boss because of your 4 piece that causes your Envenom to do 10% increased damage per bleed on your target.
Unfortunately, Assassination doesn't provide you with any notable AoE, outside of the random proc that is Poison bomb. If there's 10+ mobs present, you want to use your Fan of Knives straight into Envenoms to fish for Poison Bombs.
In cleave situations, Assassination fares a tad bit better, although not exceptionally by any means.
In raids, where in most cases you'll be specced into Agonizing Poison, if an add that isn't going to be dying within the next 15s~ is present, you want to instantly Rupture it. You should keep your Garrote for your main target as it buffs you Envenoms, but it's important that you keep 5 stacks of Agonizing Poison on the add to maximize you cleave damage. If damage on the add is not a big necessity, 1 stack of Agonizing will suffice for the energy regen from Venomous Wounds.
In 4+ target situations, it's best to use Fan of Knives to build up combo points, thus not needing to manually apply Agonizing to each mob as Fan of Knives does that for you. It's important, however, as mentioned above, that while you have Rupture running on every mob, you keep your Garrote for the priority target for the 10% extra Envenom damage coming from your Mutilated Flesh that is your 2 piece.