Mercurial the Spectre is a melee Agility hero adept at dealing pure damage to lone targets who is powerful both offensively and defensively. Spectral Dagger provides a significant amount of mobility, allowing Spectre to go through objects, units and terrain while slowing foes that come in contact with the shadowy path left by her Spectral Dagger. Desolate allows her to inflict high pure damage to enemy heroes when she catches them alone. Dispersion reduces and reflects all damage, whether by attacks or spells, to an area around her as pure damage. Dispersion gives her great durability, especially when equipped with items that provide health, armor, and damage block. Finally, her Haunt creates a malevolent spectral illusion to all enemy heroes in the map. Haunt lets Spectre wreak havoc in clashes and ganks, while her allies take advantage of the confusion. Spectre can use Reality during the Haunt, instantly teleporting her to her illusion to take its form. This lets her hound her victim anywhere on the map. Mercurial is a dangerous supernatural being, relentless as she can chase and stalk down her victim to a global range, unhindered by boundaries. Her kit allows her to play the role of the team's hard carry by applying an immense amount of pressure in late game team fights. More specifically, the pure damage reflection from Dispersion makes it disadvantageous for teams to focus her. Her abilities have a complex nature, and newer players should generally not play Spectre as she is extremely farm and level dependent. It is best to face Spectre with allied help and strength, as encountering her alone isn't always the best option.
 Recommended items
- Spectre has a weak early- and mid-game, as well as a lack of lane presence. Picking Spectre requires a team that will largely be able to hold out for a large portion of the game until you have accumulated enough major items to start fighting, so keep this in mind when building your team.
- One of Spectre's biggest strengths as a carry is her ability to participate in teamfights and ganks instantly through Haunt without wasting valuable farming time.
- The shadow path left by Spectral Dagger lets her keep track on her prey. It also slows her target and enemies who came in to the path.
- It is generally a good idea to level up Spectral Dagger first to provide Spectre with extra mobility so that she is harder to pin down during ganks. However, be wary of its mana cost, as a single Spectral Dagger will typically consume half your mana pool per cast (in the early game).
- Maxing Desolate early is the best way to increase the effectiveness of Haunt. Maxing Spectral Dagger early, on the other hand, is also desirable as its level 1 offensive capabilities are almost negligible.
- It is sometimes beneficial to leave Haunt at level 1 in the early- and mid-game. Your illusions will not be strong enough to significantly benefit from an extra one or two seconds during skirmishes or team fights, and the extra points may be better spent in your other abilities or the Attribute Bonus.
- In late game teamfights, Haunt and Desolate will allow your illusions to wither down support heroes at the back at significant speeds. In addition, you should always be in the middle of team fights to maximize the damage reflection of Dispersion.
- Don't forget that Desolate only works if enemies aren't close together. If you're playing against a Spectre, make sure to hug your ally if she comes at you to reduce her damage dramatically.
- Spectre can perform as a viable solo offlaner by using Spectral Dagger to hide in trees before creeps meet in lane, allowing you to freely leech EXP off the lane with no risk of being killed, and quickly reach level six to gank with Dagger and Haunt.
- Mjollnir adds significant farming and push potential, while filling the AoE damage role of Radiance while also scaling better and having an easier buildup. However, illusions get no benefits from it.
- Eye of Skadi provides great general attribute bonuses, solves Spectre's mana issues, and gives her a slow that penetrates through magic immunity that allows her chase and forces attention on her. The early orb of venom and point booster give Spectre great early presence, also late game.
- Skull Basher adds some damage and HP along with BKB-penetrating anticarry and chase potential that again forces attention onto her.
- Pipe of Insight makes Spectre incredibly tanky against magic damage when combined with dispersion (combined 57% resistance), and increases her teamfight presence with the HP regen and active ability.
- Armlet of Mordiggian has incredible synergy with Spectre's skill set. The HP and offensive bonuses work with dispersion and desolate respectively, which also transfer to her haunt illusions. The passive regen fills the need of a vanguard for her core, while armlet toggling provides increased HP for Spectre to disperse.
- Assault Cuirass adds extra durability and makes haunt a global -5 armor for the duration while giving any teammates in range extra armor and attack speed. The attack speed has good synergy with desolate, but does not transfer to illusions.
- The name Mercurial most likely comes from the DeviantART account of Kenneth Tan, the person who made the 6.28-6.32 loadscreen.
- "Mercurial" means "swift, shrewd, and deceitful", which is attributed to the Roman god of thieves, Mercury, as Spectre is an agile and quick Hero. It can also refer to the planet Mercury, since Spectre is an otherworldly entity. Mercurial can also hint towards the element Mercury, often called "quicksilver," which is another reference to Spectre's speed and mobility.
- Spectre's alternate/fun name "Qwerty-" was given to spectre for remembering a Legendary Dota player Zaven "Qwerty" Terminasov, who died on December 5, 2010.
- Spectre's voice responses are overlayed with the same track playing backwards, bearing a huge similarity to the Avatar of Vengeance's voice in Warcraft III: Frozen Throne, which was also Spectre's hero model in DotA.
- Spectre's ultimate sound effect it's used in the anime Ouran Host Club, episode 21.
 Update history
- Fixed Haunt illusions moving while out of the game.
- Fixed a case where leaving and rejoining the Spectral Dagger path could cause Spectre to temporarily lose no-collision.
- Added a short grace period to walking off the Spectral Dagger path before collision is restored.
- Fixed various aspects of Spectral Dagger logic being dispellable.
- Fixed Spectral Dagger sometimes creating invisible paths of targets it hit.
- Spectral Dagger now properly trails invisible units.
- Fixed various properties of Haunt illusions being incorrect.
- Updated vision values on these abilities: Unstable Concoction, Phantasm, Waveform, Storm Hammer, Mirror Image, Spirit Lance, Requiem of Souls, Spectral Dagger, Venomous Gale, Earthbind, Dream Coil, Shackleshot, Wall of Replica, Flamebreak, Deafening Blast, Ghost Ship.
- Fixed being unable to Reality to a sleeping Haunt illusion.
- Fixed Haunt Illusions having collision.
- Fixed turn rates for the following heroes: Lifestealer, Alchemist, Clockwerk, Bounty Hunter, Dark Seer, Dazzle, Ancient Apparition, Brewmaster, Chen, Silencer, Lone Druid, Spectre and Spiritbreaker.
- Updated attack animation for Spectre, with more impact on hit frame.
- Fixed permanently losing the ability to block creeps after the first Spectral Dagger use.
- Fixed Haunt not working properly after a disconnect.
- Fixed Reality clearing Curse of the Silent and triggering Magic Stick.
- Added more movement lines for Dazzle, Dark Seer, Dragon Knight, Furion, Huskar, Riki, Skeleton King, Slardar, Spectre, and Jakiro.
- Fixed Heart, Urn of Shadows, and Dagger not being properly Disabled by Haunt.
- Fixed Spectre rising to flying height when walking on a dagger path.
- Fixed Haunt illusions not dying when their targets die.
- Fixed some size issues with Spectral Dagger.
- Fixed illusions not delaying 1 second before attacking.
- Desolation now happens when the attack is executed, rather than when it lands.
- Dispersion no longer works on ancients or Roshan.
- Gave path 500/500 flying vision.
- Heroes only trail the path for 7 seconds, not 12 like the dagger does.
- The path radius is now 150, rather than 125.
- The debuff should last for 4 seconds on enemies now, rather than 7.
- Fixed creeps trailing paths from Spectral Dagger.
- Fixed Reality being learnable at level 1, allowing you to cast Haunt.
- Fixed Spectral Dagger being dodgeable.
- Fixed Dispersion from working on Roshan Ancients.
- Fixed Dispersion not triggering damage events like Dagger and Potions.
- Fixed Haunting on enemy illusions.
- Fixed Haunt illusion movement speeds.
- Desolate no longer works on creeps.
- Fixed Blink Dagger's cooldown not being triggered by Spectre's Haunts.
- New Hero: Spectre.
 Balance changelog
- You can now continuously use it on your illusions.
- Cast point improved from 0.3 to 0.
- Haunt no longer ends when you use reality (the targeted illusion is still replaced by you though).
- Desolate damage increased from 20/30/40/50 to 20/35/50/65.
- Dispersion damage no longer disables items like Blink Dagger.
- Undid melee hero collision change from 6.72c
- Melee hero collision size now reduced from 24 to 12.
- Rebalanced all Melee heroes between 100 and 128 range to be 128 range
- Spectre previously had 100 range.
- Reworked Dispersion:
- Damage is split amongst the number of heroes in the area.
- 10/14/18/22% of damage taken is reflected
- 1000 AoE
- Damage reflected decreases based on how far heroes are from you. Full damage at 300 range then decreases gradually till 1000 distance away.
- 10/14/18/22% of damage taken is reflected
- Desolate damage increased from 15/25/35/45 to 20/30/40/50.
- Dispersion reflection increased from 5/10/15/20% to 10/14/18/22%.
- Desolate's search AOE improved from 400 to 350.
- Dispersion now spreads the reflected damage over the number of nearby heroes. So it is the same in a 1v1 case, but greatly reduced in team fights.
- Decreased Spectral Dagger cooldown from 25 to 16 seconds.
- Restored some vision back to Spectral Dagger path.
- Spectral Dagger no longer gives vision.
- Reduced Illusions' damage from 50% to 40%.
- Now has a 1 second delay during which they fade in before the images start attacking the targets.
- Rebalanced Haunt cooldown (150/120/90 to 120).
- Increase AOE on Dispersion.
- Changed Dispersion.
- Reduced area that is used to check if a hero is alone with Desolate
- Reduced Agility/Level on Spectre
- Minor armor buff (usually 1) to most melee heroes
- Spectre base damage reduced.
- Reduced duration of Spectral Dagger's hero trail and initial cast trail durations.
- Removed Dispersion from images
- Slight nerf to level 3 Haunt
- Reworked/Improved Bristleback, Avernus and Mercurial
 Old Abilities
The only thing known about these is that Spectre had them in 6.30. This cannot be proven though, as playdota's changelog does not go below 6.48.
 See also