* Worms are Exotic
* Worms are mainly PvE AoE pets
* Burrow must be used manually
* Burrow makes the worm untargetable
* Burrow costs 30 focus
* Kill Command & other pet utilities break burrow
* What is a worm & what does it do?
Worms are exotic (limited to Beast Mastery hunters) beasts that have shot up in popularity as PvE pets in recent months. The reason for this was a buff to their already-powerful AoE attack, Burrow. A worm correctly used by a BM PvE player is a must-have--it can put out extreme amounts of damage (100k+ dps in burst). The only other pet which comes close is the Chimaera, which suffers from having its attack only affect enemies in a short cone in front of it. On the upside, the Chimaera's attack has no cooldown, and can be used while moving, whereas the worm's Burrow can be used 8 of every 21 seconds for a properly-specced hunter, and which must be channeled in place.
* Where can I get a worm?
Remember that worms are Exotic, so you cannot tame them unless you are Beast Mastery, and have the talent point (last in the tree!) to tame Exotic Pets. Worms come in two varieties, but both are identical game-play wise--the difference is only in appearance and location. The first is the Old World worm, a vanilla model--a slick, glowing-eyed worm type with powerful mandibles, often found in dark, damp places within dungeons. The second is a larger, coarse-skinned worm known as a Jormungar, with a line of thick hair down the spine and spikes along its sides. These are found in the cold, snowy climate of Northrend. Worms of either type can come in a variety of colors, with one--the Disembodied Jormungar--even coming in a "ghost" flavor!
Check out Petopia's Worm page for more information & locations for each appearance type.
* Where & how do I use my worm?
Worms should be used for AoE on large groups of mobs in PvE, whether that PvE be raids, dungeons or solo-questing or grinding.
The worm is not traditionally a PvP pet. Theoretically, a dps-specced worm could provide good damage output on large groups in PvP, as well as allowing the use of Intervene and Roar of Sacrifice. However, the damage output on single targets will be lower than that of a properly-specced Ferocity or Cunning pet, and the worm's special ability does not provide any added utility (like a heal or a root) for PvP situations. The worm could potentially be used to break up large groups camping a single spot, like a flag point, since moving off of the worm's AoE prevents damage. If you'd like to use a Worm in battlegrounds it's advisable to bring along other pets to switch to when fighting 1-on-1.
On to the "how!"
First of all, know that the worm's big AoE attack (Burrow) must be used manually. It cannot be set to Auto-cast, so leave it on the pet's action bar, or make a macro for it on your own bars.
Next, be aware that the Burrow costs your pet 30 Focus. Therefore, it's best to keep the worm on Passive just before Burrowing to ensure that Burrow can be used as soon as you're ready for AoE burst. If your tank is going to pull a pack of mobs to a specific location, try positioning your worm there in advance with the Move To command (assuming moving your pet will not aggro other nearby enemies!). Sending him in with the "move to" command rather than "attack" ensures he will not be too low on focus to use Burrow. After moving the worm, pop all damage-increasing cooldowns and use Burrow, and gaze in awe at the huge numbers!
Burrow makes the worm untargetable, meaning that if you use the worm's Burrow and then Feign Death, the enemies will all Evade. In addition, if you use Burrow while you yourself are standing far away, the mobs will move to you, leaving the worm's AoE range and taking no damage. Your best bet is to tag with Multi-shot, then move in close and use Burrow, using Deterrance as well if you expect high incoming damage.
Something to bear in mind: as tempting--or automatic--as it is to use Kill Command or other pet-related abilities (such as Master's Call), don't--they will cause the worm to cease Burrowing in order to obey. As Burrow has a cooldown (albeit a short one), that's a big DPS loss! The best use of a Worm is to bring it along in PvE and only switch to it for large AoE pulls; use your other DPS pets for bosses and smaller trash pulls.
Lastly, remember that Burrow is a damage ability, and that the worm--despite being a Tenacity pet--is used for damage in raid and dungeon environments. So for DPS, you'll want to talent it for pure damage, rather than survivability, although chances are you'll have to pick up a tanking talent or two in order to progress through the tree. Be sure to take Serpent's Swiftness, Spiked Collar, Culling the Herd, Wild Hunt and optionally Thunderstomp (this last helps when soloing, or can be used for a bit of extra damage after Burrow is over; it can be toggled off when needed).
* What is living with a worm like?
Well, for one thing, they're adorable. Sure, it's all about perspective, but they use the Serpent animations, meaning they tend to look around from time to time, tilting their heads--it's quirky and cute. The Old World worms have a charming grin to them, almost mischevious. The Jormungars don't have visible eyes, so they may come across as having somewhat less personality to some, but their animations are still quite cute. That said, the darker-colored Jormungars can appear rather menacing--if you like a wicked-looking pet, check out the black Jormungar.
A good number of the color patterns are aesthetically pleasing, too--the Old World worms come in a wide variety of bright gold/black, teal/black, blue/white and so on, all with complimenting eye colors. The Jormungars come in blue, purple/pink/blue, white/lavendar, black, ghostly, and more. Strangely enough, some of the Jormungars' "manes" seem to be unaffected by lighting, causing for example the black Jormungar to have bright gray-white hair in dark areas.
Worms are tall pets--moreso with Jormungars, which are also rather bulky. They tend to actually tower above their hunter companions. They aren't very broad, though, so they won't often interfere with targetting. Their sound effects are unique, but not loud or overpowering--a series of grunts and gravelly growls.
When Burrowing, the worms dive beneath the ground and leave a tumbling pile of rocks and pebbles until they surface again. Utility-wise, they make excellent grinding and PvE pets, and so keeping one with you at all times isn't a bad idea at all.
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All in all, worms are useful and charming pets, a must-have for BM PvEers, and come in enough appearances and colors that anyone's taste will likely be satisfied!