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Gaile Gray


This is a guide on solo blocking wurm projectile attacks as an elementalist. While it is written with Cobalt in mind, the theory and techniques here apply to all wurms. Emphasis is placed on learning, understanding, and improving, not obtaining results.


  • Fun: A reflector or reflect team is sitting idle for most of the wurm event.
  • Challenging: There are no other PvE activities in Guild Wars 2 that require the precise positioning and timing needed to perform this role. Moreover, the focus required needs to be maintained for 14 minutes.
  • You potentially handle two defensive roles at wurm, something that some guilds regularly assign up to 10 players to handle. That's a lot of efficiency! This has been utilized to great effect.


  • Basic knowledge of ele gameplay
  • Understanding of wurm attack mechanics
  • Mastery of solo reflecting and all associated prerequisites
  • Patience. Lots of patience.

Wurm Attacks[edit]

Understand the wurm attacks you will be responsible for neutralizing. The names used here are what they'll be called in the rest of this document.

Name (combat log name) Tango-recharge-darker.png Cooldown [1] Attack Duration (approx.) Reflectable? Blockable?
Cobalt Amber Crimson
Egg (Spit) 45 sec 50 sec 50 sec 3 sec 1Yes 1Yes
Spit (Drool) ? 25 sec 25 sec? Instant 0No 1Yes
Husk (Disgorge Husk) 90 sec 100 sec 100 sec 3 sec 0No 1Yes
  1. ^ Not definitive. These are best guesses based on observation.

Invulnerability blocking[edit]

Blocking Mechanic

Any projectile (eggs, spit, or husks) from the wurm has a point of origin. From there, they travel in an arc towards a target point. If the projectile collides with an invulnerable unit in-flight, the projectile is absorbed and ceases to exist. Invulnerability blocking refers to standing at the point of origin of these wurm attacks, becoming invulnerable, and absorbing the projectile.

Note: the combat log will describe projectiles as being "absorbed". In this document, I will refer to them as being "blocked".

Sequence of Actions
  1. Dodge the previous attack into the wurm (if you didn't block it).
  2. Zoom in.
  3. Calibrate your position.
  4. Zoom out.
  5. Activate your invulnerability skill as the projectiles are released.

All of this needs to be done within a few seconds. Familiarity of this sequence will gradually happen over time.


These are the skills you'll be working with:

Skill Tango-recharge-darker.png Cooldown (Traited) Type Duration Tango-activation-darker.png Activation Time Notes
Swirling Winds.png Swirling Winds 30 (24) Reflect 6 sec 0.5 sec Try to only use this skill against the egg attack.
Obsidian Flesh.png Obsidian Flesh 50 (33.5) Block 4 sec Instant
Fortify.png Fortify 30 [1] Block 3.3 sec (approximate, see note) 0.2 sec (approximate) The duration is slightly longer than the channeling bar would indicate.
This is your most versatile option as it has the shortest cooldown and can fully block every attack. Unlike the other skills, you can't move while channeling this.
Mist Form.png Mist Form 75 Block 3 sec (see note) Instant I am unable to reliably use this skill to block a full husk or egg volley. Consequently, I only use it for blocking spit and recovering from mistakes.
  1. ^ Cast Conjure Earth Shield where you can pick it up immediately. After using this skill, you will always either be able to pick up the one on the ground, or reconjure the shield again.

Having Geomancer's Alacrity will allow you to block more than otherwise. Aeromancer's Alacrity serves no purpose given the egg attack's cooldown.

Feedback (not the Mesmer skill)

When you successfully block a projectile, you will be notified in two ways:

  • The combat log
  • An "Invulnerable!" message appear near your character.

One or both of these should be used to determine which attack the wurm used. It is not recommended that you look for actual projectiles, because you cannot distinguish between a husk or egg attack when all projectiles are successfully blocked.

This sequence shows a dodged spin, blocked eggs, blocked husks, and blocked spit.
Proper positioning when facing the cliff at Cobalt. Click for larger image.


Successful blocking requires you to stand at a specific location. When starting out, it is not uncommon to miss some projectiles because they have slightly different points of origin. Despite that, there exists a location that will allow all projectiles to collide with you. Learn to quickly find this spot and plant yourself there.

Practice and Improvement
For consistency, I recommend always facing the same direction. When zoomed in, use the two boulders sticking out as reference points. Resist the urge to repeatedly zoom in and out to readjust your position.
When starting out, you may be tempted to move left-to-right to follow the wurm's attacks. While this may be safer, you will end up learning the correct position slower, so I don't recommend it. Moreover, this technique does not work with Fortify.
The shield auto-attack chain will alter your position. Specifically, the second attack in the chain Shield Smash will move you towards your target. If you have an enemy targeted, you risk being moved out of position. Never have anything targeted while blocking.
During a burn phase, resist the urge to move if you don't need to. It will be harder to be ready for the next attack with all the skill effects and player models centered on the wurm.

Timing and Duration[edit]

Blocking spit is easier than blocking husks because that attack has a very small duration, so I recommend starting out trying to block that first. Work towards blocking entire husk volleys afterwards.

Practice and Improvement
Words can't really describe the precise moment to activate your skill. You could watch a video to "know" the right timing, but you don't become better at execution. Practice is the only way to master this. While there is no shortcut, here are various tips I've picked up along the way.
  • Become intimately familiar with the activation time of your block skills. This will allow you to to activate them as late as possible to cover a whole volley.
  • The moment an "invulnerable" message appears is when you successfully blocked a projectile. Understand when they appear (when the projectiles are created) in relation to visual and auditory cues from the wurm.
  • As you get better, blocking with Obsidian Flesh will become "easy" due to its longer duration. When you can consistently block with Obsidian Flesh, it's time to start doing so with Fortify. Don't become complacent and stick to only using Obsidian Flesh.
  • As you become more familiar, start using your cooldown recharge time as a reminder of upcoming wurm attacks.
  • You can immediately use Obsidian Flesh or Mist Form after another blocking skill to catch the tail end of a mis-timed block. While this is a good emergency option during a "live" raid, it is wasteful. Don't get into the habit of relying on this.
  • Ironically, the attack that you are already very good at neutralizing (eggs) is the hardest one to block. Some egg projectiles have a slightly different point of origin than others. A position that suffices for completely blocking spit or husks may miss 1 or more eggs. The upshot of all this is that you should always strive to use swirling winds on the egg attack. This may not always be possible, so it is still useful to be able to block egg attacks with Fortify.
  • Mistakes will happen. Embrace them.

Solo Block Scheduling[edit]

Once you've mastered blocking each attack individually, the last step is to learn to schedule your skill activations so you can block (nearly) everything. At this point, you should already have a good sense of:

  • what situations calls for which skill
  • your skill recharge rate and when they finish relative to upcoming attacks
  • which sound is associated with each attack
  • how to deal with mobs that aggro onto you
  • how to recover from mistakes

To solo block, you need to keep a mental model of the wurm's skill cooldowns. This allows you to stop "reacting" to possible attacks and start knowing what will happen next. In doing so, you no longer need to "save" skills in anticipation because you know exactly what the wurm is capable of doing next. To accomplish this, you need to be able to block without giving it much thought. Movement and skill activation should be muscle memory.

I use two systems for tracking the wurm's attacks. I don't claim they are either the easiest to learn or the most efficient. They are simply what I developed.

Method 1: Focus on the Husk Attack Cooldown[edit]

This works based on a simple principle: Since your Swirling Winds cooldown (30) is less than the egg attack cooldown (45), it will always be ready to block eggs. You follow these simple rules:

  • When you block a husk volley (this happens within the first 3 attacks), look at the event timer. Subtract 1:30. That's when you need to be ready to block the next husk volley.
  • At all other times, if the wurm is coughing up something, it is guaranteed to be eggs, so have Swirling Winds ready for that.
  • With the remaining skills, block as many spit attacks as possible.

Method 2: Track Cobalt Attack Cycles[edit]

Update 6/23/15: After the core specializations update, which introduced Geomancer's Training, there is a lot more freedom for scheduling blocking skills. Specifically, it is now possible to block every single projectile attack from Cobalt.

This method is based on a simple concept: While Cobalt has 4 attacks with different cooldowns, there is very little randomness to its sequence of attacks. This method attempts to reduce the uncertainty by keeping track of attack patterns over a longer period.

  • Since the husk attack has the longest cooldown at 90 seconds, we define an "attack cycle" as all the attacks that start with a husk attack and end right before the next husk attack.
  • Within an attack cycle, the wurm's sequence of attacks is deterministic.
  • There are only 3 distinct attack cycles. For the sake of simplicity, I'll label them by the first few attacks within the cycle:
    1. Husk-Egg
    2. Egg-Husk (Okay, I lied. This breaks the definition I gave above. Just think of this as Husk-Egg, but with the first 2 attacks switched. Everything else is nearly identical between these two.)
    3. Husk-Spin-Egg: The spin is the "large spin".
  • Each attack cycle can only transition into one other attack cycle. (There's an exception to this: see below.)
  • All of the above means there are only two situations when the wurm can be unpredictable: the very first attack cycle, and the exception.
  • Okay, I lied again. When your group enters a burn phase, none of the above is valid anymore. You'll need to fall back to method 1 until:
    • You identify which attack cycle the wurm settles into. Resume tracking with this method.
    • If the wurm's attack pattern doesn't fall into any attack cycle, you will have an easier time distinguishing husk and egg attacks because their cooldowns will finish recharging further apart.
    • Your group enters another burn phase.

Here's how attack cycles transition into each other. As you can see, Egg-Husk is the problematic one because it can transition into two possible cycles.

User Ventaurion SoloEleBlock Attack Cycle Transistions.png

And here's how to treat each attack cycle:

Attack Cycle Can start with this? Next Attack Cycle Sequence of Attacks/Responses [1] Notes
Husk-Egg 1Yes Husk-Spin-Egg husk Obsidian Flesh.pngegg Swirling Winds.pngspit Fortify.png → spin Dodge.pngspit Obsidian Flesh.pngegg Swirling Winds.png → spin Dodge.pngspit Fortify.png This cycle gives you enough time to use Obsidian Flesh twice.
Egg-Husk 1Yes Egg-Husk or Husk-Egg egg Obsidian Flesh.pnghusk Fortify.pngspit Mist Form.png → spin Dodge.pngspit Fortify.pngegg Swirling Winds.png → spin Dodge.pngspit Dodge.png → spin Dodge.png Ideally you use Swirling Winds to block the egg, but you can never tell whether this attack cycle or Husk-Egg will happen.
Therefore, always start with Obsidian Flesh. The response sequence given here is "eager blocking" of spit.
In actuality, you have one Fortify and one Mist Form skill to block 3 spit attacks, so one spit attack will always get through no matter how you schedule.
Husk-Spin-Egg 0No Husk-Spin-Egg husk Obsidian Flesh.png → spin Dodge.pngegg Swirling Winds.pngspit Fortify.png → spin Dodge.pngspit Mist Form.pngegg Swirling Winds.png → spin Dodge.pngspit Fortify.png This is the terminal attack cycle. It keeps repeating itself until either the event ends or a burn phase occurs.
  1. ^ Dodge.png dodge

Some Theorycrafting/Speculation[edit]

Wurm skill priority and its effect on determinism
The wurm uses each skill as soon as it can. When multiple skills are available for activation, there is an activation priority. The egg and husk attacks have equal and highest priority. Spit is next, followed by spin. This is why there are situations when either Egg-Husk and Husk-Egg can happen: both skills are ready to activate, and one is chosen randomly. This is also why the wurm's attacks are so predetermined by its initial choice of attacks.
Why method 2 was developed
Ignoring spit attacks, the main difficulty in blocking both eggs and husks is that their attacks are indistinguishable. Moreover, when both attacks are ready, either one can be activated. The need to discern them was what led me to develop method 2: the uncertainty of the next attack becomes drastically reduced.
Applicability of method 2
If a burn phase triggers at the right moment and husk/egg attacks recharge sufficiently far apart, it becomes easier to know which attack is coming next, and method 2 is no longer worthwhile.
Method 2 should be easily adaptable to Crimson and Amber. In fact, since their projectile attacks have a longer cooldown, I believe it will be easier to block everything


These are intentionally imperfect sessions, as they are more illustrative of how to react to different scenarios. Includes misc. commentary.

Misc. Notes[edit]

  • When activating a skill to block spit, activate it as early as possible. This allows it to be ready for the next activation earlier.
  • At a live raid, you may be attacked by other mobs. Be aware that they may trigger extra "invulnerable" messages.
  • Magnetic Wave.png Magnetic Wave can remove condi. Much like a guardian's Shield of Absorption.png Shield of Absorption, this can reflect a limited number of eggs.
  • Do not practice when someone else is blocking/reflecting. The mixed feedback will make it unclear how well you are doing.
  • Ash Legion Spy Kit helps for dropping aggro. Remember to stand still. Harpy Feathers is another alternative.

Thanks to Eilus for general feedback.