Elemental, Shaman, Theorycraft, WoW

Elemental: Spell mechanics

Another boring post today, this time about the sometimes quirky core mechanics of elemental spells.  Tomorrow I’ll be doing a more detailed look at the elemental talent tree.  In the meantime, I refer you to my basics guide on Talents & Glyphs; you could also check Healing Way’s fun Thunderstruck feature on elemental talents, though the crit damage bonuses are listed incorrectly (tsk!).  But there are pictures so all is forgiven.

I’ll discuss the concept of spell travel times and the basics of interaction with buffs/debuffs and procs before moving on to deal with specific elemental spells.  At the end I’ll collate it all into a table for reference.  This stuff may seem arcane and irrelevant, but understanding it can have a serious benefit to your damage and ability to cope with aspects of encounters!

Before we start, you can enjoy this nice relaxing picture of Yogg-Saron’s shattered prison.

Pretty!

Flight times

The first thing to understand about elemental spells is the concept of a travel time, or a delay between finishing a spell cast and having that spell arrive at the target.  Some spells have a travel time, and others reach their target instantly.  If you ever played Quake 2, you can think about it as the difference between the rocket launcher and the railgun: the railgun’s instant, the rocket launcher has a flight delay.  For us elementals, only Lava Burst and Lightning Bolt have a flight time; all our other spells reach their target instantly when the server decides your cast has finished (which may not agree with when the client decides the same).

I’ve not seen any numbers, nor have I tested it, but at 30 yards range the flight time on a spell seems to be about a second.  The spell will hit when the animation hits.  However, there seems to be a cap on flight time: even if the animation does not hit for a long time (say, if your target is flying away on an epic mount), the spell effect will hit after a fixed, short arbitrary amount of time has passed.

Interaction with temporary (de)buffs and procs

Note: a “proc” is a temporary effect which occurs as a result of something happening in the game, such as a spell cast or being hit by a monster.  If something “procs” it activates its special temporary effect.

On Start casting

For spells with a cast time, any buffs or temporary effects which could affect the spell’s casting time are applied when you start casting.  If you’ve got 1 second left on your Embrace of the Spider buff and you start casting a 2-second Lightning Bolt, only for the buff to fall off before the spell finishes, it will still receive the buff as it was present when the cast began.  This is easy to observe as you can see the spell casting quicker.

On End casting

The basic check for how much damage a spell does is done when it finishes casting – critical strike chance, debuffs on a target, your spellpower at the time, etc.  Trinkets and other proc effects that depend on “casting a spell” are activated when you finish casting.

On Hit

Any effect which talks about “when you deal damage” applies only when the spell actually hits a target which, if the spell has a flight time, might be a second or two after you finish casting.  Spell reflects, mobs that gain buffs/debuffs on hit (e.g. Freya’s Snaplashers) and so forth all occur when a spell hits.

Absorption shields, buffs/debuffs with charges and immunities are also calculated on spell hit.

Scary Lightning

Notable spells & related effects

Lightning Overload activates on spell hit Chain Lightning overloads pick their secondary targets independently to the parent spell because it is a totally new spellcast.  Chain Lightning has an 11% chance per target hit to proc Lightning Overload, for a total 33% chance over the whole spell.  Lightning Bolt targets that move out of range during the flight time between end cast and spell hit cannot proc Lightning Overload as the check is performed on hit, and the target is out of range.

Lava Burst checks to see if Flame Shock is active on end casting.  If your lava burst finishes casting before Flame Shock expires, it will crit even if the spell only hits the target after Flame Shock has expired.

Flame Shock‘s damage-over-time tick crit chance (with glyph or set bonus) and damage are calculated based on your spellpower and crit chance when the spell is cast.  Casting a new Flame Shock while the DoT is still ticking will reset the tick timer and damage calculations to start from the moment of the new cast.  Flame Shock’s DoT tick crits cannot trigger our various crit-triggered talents like Elemental Focus or Elemental Oath.

Searing Totem, Magma Totem, Fire Nova Totem and Fire Elemental Totem deal damage based on your spellpower and crit chance at the moment of casting.

Clearcasting from Elemental Focus is activated on spell hit.  The buff is only taken into account on start of cast.  Thus it is likely that the first spell you cast after Lava Burst will not be affected by Clearcasting due to flight time delaying the buff’s proc.  However the second and third spells will be properly affected.  Lightning Overload can benefit from Clearcasting but does not consume its charges.  Note that even if you have Moonkin Aura you will still receive the 10% damage buff from Elemental Oath.

Wind Shear and Elemental Mastery do not trigger the Global Cooldown, meaning spells can be chained immediately afterwards with no delay.  They can also be used while you’re waiting for a GCD to expire.

The Global Cooldown triggers immediately upon the start of casting, even if the spell does not finish casting.

Spell queueing, latency and cooldowns

Since patch 2.3, it is possible to queue the next spell to be cast before your existing spell finishes casting to compensate for client-server latency.  This means if you have 300ms of latency to the server, you can start casting your next Lightning Bolt while your existing cast has 0.3 seconds left before it completes!  However this seems to be limited by client-side cooldowns: if you have a latency of 300ms and Lava Burst comes off cooldown in 0.2 seconds’ time, you cannot queue the Lava Burst to cast until the client is satisfied that it is off cooldown, ie in 0.2 seconds’ time.  The same applies to the Global Cooldown.

A spell mechanics table

Spell Flight Time Base Cast Time (s)
Procs Affected by
Lightning Bolt Yes 2.5 Lightning Overload LB (on hit)Clearcasting (on hit) Thundering Strikes (enhance), Frozen Power (enhance), Maelstrom Weapon (enhance), Concussion, Convection, Elemental Focus, Elemental Fury, Eye of the Storm, Elemental Reach, Call of Thunder, Elemental Precision, Lightning Mastery, Lightning Overload, Shamanism, Tidal Mastery (resto)
Lightning Overload LB Yes Instant Clearcasting (on hit) As above.
Chain Lightning Instant 2.0 Lightning Overload CL (on hit)
Clearcasting (on hit)
As above, plus Storm, Earth and Fire
Lightning Overload CL Instant Instant Clearcasting (on hit)
As above (but not Storm, Earth and Fire).
Lava Burst Yes 2.0 Clearcasting (on hit) Thundering Strikes (enhance), Concussion, Convection, Call of Flame, Elemental Focus, Elemental Fury, Eye of the Storm, Elemental Reach, Elemental Precision, Lava Flows, ShamanismCrits if target affected by Flame Shock at end of cast.
Flame Shock Instant Instant (GCD) Clearcasting (on hit)Lava Flows (on dispel) Thundering Strikes (enhance), Shamanistic Focus (enhance), Frozen Power (enhance), Mental Quicknes (enhance), Concussion, Convection, Call of Flame, Reverberation, Elemental Focus, Elemental Reach, Elemental Precision, Storm Earth and Fire, Booming Echoes, Lava Flows
Frost Shock Instant Instant (GCD) Clearcasting (on hit) Thundering Strikes (enhance), Shamanistic Focus (enhance), Frozen Power (enhance), Mental Quicknes (enhance), Concussion, Convection, Reverberation, Elemental Focus, Elemental Fury, Elemental Precision, Booming Echoes
Earth Shock Instant Instant (GCD) Clearcasting (on hit) Thundering Strikes (enhance), Shamanistic Focus (enhance), Frozen Power (enhance), Mental Quicknes (enhance), Earthen Power (enhance), Concussion, Convection, Reverberation, Elemental Focus, Elemental Fury, Elemental Precision

Wow, I think that table was a giant waste of time.  Yes, I confusingly listed all the talents which affect those spells, even those not taken by elementals. No, I didn’t mention things like Elemental Oath or Elemental Devastation (which is an enhancement talent in the elemental tree) which proc from all (non periodic) crits. I also didn’t mention Dual Wield Specialisation (enhance). Ain’t I a stinker.

There’s more information on general spell casting mechanics in the aptly-named Spell Casting Mechanics entry in the Theorycrafting Think Tank at ElitistJerks.

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