Zet, the Arc Warden, is a ranged agility hero that requires micromanagement and farm to spiral out of control. In the early stages of the game, it is a very powerful nuker. Its first ability, Flux, allows Arc Warden to cripple an enemy down and deal large amounts of damage. It and other allied heroes or buildings can be protected from physical attacks with its second ability Magnetic Field, while gaining swift attack speed. Similar to Techies' Land Mines, Arc Warden's third ability, Spark Wraith, allows it to place wraiths that attack when an enemy goes near them, potentially dealing large amounts of magical damage. Finally, thanks to its ultimate, Tempest Double, which allows it to make a perfect copy of itself that can use all of Arc Warden's spells and item abilities, it can spam all of its other abilities and most items twice and easily take down fragile heroes in the early game, or keep itself or its team doubly sustained through certain buffing or healing items. This makes Arc Warden very powerful in both early and late game if given enough farm, from magical nuker to physical carry, or if the time calls it, a very potent support.
History
Before the beginning of all, there existed a presence: a primordial mind, infinite, awesome, and set to inscrutable purpose. As the universe thundered into being, this mind was fragmented and scattered. Two among its greater fragments--who would come to be named Radiant and Dire--found themselves locked in vicious opposition, and began twisting all of creation to serve their conflict.
As war and cataclysm threatened the nascent cosmos, the will of a third fragment made itself known. Naming itself Zet, this intellect sought to resolve the disharmony and return all to perfect unity. Appalled by its kin's conflicting nature, Zet gathered the sum of its power. In a sudden flash, it overwhelmed its siblings, and fused the warring aspects into a stellar sphere before hurling them into the darkness to orbit a nondescript world. Harmony was restored, though only the barest fraction of Zet's strength remained. Setting its gaze on the prison, Zet chose to use its weakened power to serve as watchful warden until time's end. For uncounted aeons, this vigil stood.
Life flourished upon the world below, oblivious to the dangers imprisoned within the softly glowing moon, or of Zet's struggles to contain them. As the captives' eternal clash reverberated within, the surface of the prison shuddered, over time beginning to crack. Ultimately, Zet's depleted power proved insufficient to contain the breach, and at last the moon was shattered. The prison's ancient inhabitants had escaped to sow their conflict anew.
Flung to the farthest reaches by the prison's explosion, Zet was transformed by the dissonant energies of its former captives. No longer of single form and thought, its presence had become split among many--some lesser, some greater--each connected by a fleeting arc of consciousness. Struggling to suppress its own disunity, Zet sped toward the burgeoning conflict of its siblings, bending its fractured wills toward a singular conclusion: the aspects of the primordial mind must be made to reunite, or all must be destroyed lest the conflict spread further…
Abilities
Flux
Q
C
Infuses a lone enemy unit with swirling, volatile energy, slowing its movement speed and dealing damage over time. The effect is muted if another enemy unit is near the target.
Cast Animation: 0.3+0.77
Cast Range: 600/700/800/900
Search Radius: 225
Damage per Second: 15/30/45/60
Move Speed Slow: 20%/30%/40%/50%
Duration: 6
18
75 Slow persists and attempts to deal damage if debuff was placed before spell immunity and when not dispelled.
Modifiers
Flux: Dispellable with any dispel.
An infinitesimal fraction of the power which imprisoned the Ancients.
Notes:
- If the target has allies or neutral creeps within a 225 radius, the spell temporarily stops slowing and damaging the target, until it is alone again.
- Checks for enemies and neutrals, updates the slow and deals 7.5/15/22.5/30 damage in 0.5 second intervals, starting immediately upon cast, resulting in 13 possible instances.
- Nearby buildings, wards and hidden units are ignored and do not mute the effects. Invulnerable units, however, are not ignored.
- Can deal up to 97.5/195/292.5/390 damage to the target if all instances are applied (before reductions).
- Multiple casts on the same target fully stack, with all instances working independently from each other.
Magnetic Field
W
F
Generates a circular distortion field of magnetic energy that protects allied heroes and buildings within it by evading attacks coming from outside the field.
Cast Animation: 0.3+0
Cast Range: 900
Effect Radius: 275
Evasion: 100%
Attack Speed Bonus: 50/60/70/80
Duration: 3.5/4.5/5.5/6.5
35/30/25/20 110 Evasion affects illusions, attack speed does not.
Modifiers
Magnetic Field: Undispellable.
Time and space are of little consequence to one as old as Zet.
Notes:
- Applies an attack speed bonus and evasion to allies within the radius.
- The effects are provided by an aura. Its buff lingers for 0.1 seconds.
- Only affects heroes and buildings. All other units are completely unaffected.
- Does not evade attacks landing on allies when the source of the attack is within the field.
Spark Wraith
E
R
Summons a Spark Wraith that slowly materializes and patrols a targeted area until an enemy comes within its range. Once a target has been found the wraith fuses with them, dealing magical damage and purging the unit.
Cast Animation: 0.3+0.77
Cast Range: 2000
Search Radius: 375
Activation Delay: 2
Move Speed Slow: 100%
Damage: 100/160/220/280
Slow Duration: 0.4/0.5/0.6/0.7
Wraith Duration: 50
4 80 Attempts to deal damage if target turns spell immune before impact.
Modifiers
Satyr Trickster Purge: Dispellable with any dispel.
Lesser fragments of Zet's original self.
Notes:
- The Spark Wraith travels at a speed of 400 and cannot be disjointed.
- Once the activation delay is over, it checks for enemies (including neutral creeps) in 0.2 second intervals and launches towards the first registered enemy.
- If multiple enemies are within range after the delay, the closest enemy is targeted.
- The slow does not stack with the slow of
Purge, due to it using the same modifier as the Satyr's Purge.- If the Purge is already applied, Spark Wraith does not slow, unless its slow duration would exceed the remaining duration of the Purge's slow.
- Note that Spark Wraith does not apply any dispel. It only slows. The Purge debuff in this case is only applying the slow.
- The Spark Wraith is fully visible to the enemy.
- Fully affects invisible units. Can target units inside the Fog of War, but not invulnerable or hidden units.
- The activation delay is not included in the wraith's duration.
- Provides 300 radius flying vision for its full duration. The vision does not linger.
- The launched projectile also provides the same vision, which lingers for 3.34 seconds after reaching the target.
Tempest Double
R
D
Briefly refocusing its fractured elements into a single form, the Arc Warden is able to create a perfect electrical duplication of itself. The duplicate can use all of Arc Warden's current items and spells, except items that drop on death. The duplicate has separate item and ability cooldowns.
Cast Animation: 0.15+0.5
Number of Doubles: 1
Duration: 12/14/16
40/35/30
Warped by the power of its peers, Arc Warden becomes what it despises most: disharmony.
Notes:
- The Tempest Double always spawns with Arc Warden's current mana and health.
- On the first cast of Tempest Double, the double is actually summoned. On every following cast, it is just healed or revived.
- This means it is impossible to create more than one double at a time, since recasting Tempest Double merely replaces the one from the previous cast.
- The double also gets fully dispelled, getting freed from absolutely every buff and debuff, including usually undispellable ones.
- Its cooldowns are not refreshed upon getting re-summoned, so all cooldowns from the previous cast carry over.
- The Tempest Double is visually distinguishable from the original Zet for enemies, just like how it is for allies.
Refresher Orb and this spell are always on cooldown for the double, so it is impossible for it to create its own double.
- The buffs of a consumed
Moon Shard and an 
Aghanim's Scepter granted by 
Alchemist are copied as well.- However, other permanent buffs (e.g.
Duel, 
Intelligence Steal) are not. - Any Duel victory damage the double gains during its uptime is lost upon death.
- However, other permanent buffs (e.g.
- The double itself is treated exactly like a hero by all spells, since it is not an illusion.
- The double has a fixed 160 gold and a 160 experience bounty. It does not change based on level and is only granted to the killing unit.
- Denying the Tempest Double grants the bounty gold to the denying ally, but not the experience.
- Spell effects, that grant bonuses when an enemy unit dies (such as
Sadist), do not grant any bonuses for killing the double.- This non-crediting also prevents Duel from granting damage when the double loses.
- It also does not grant
Track bounty when it dies while tracked. - The upgraded version of
Wrath of Nature only spawns a regular Treant (not a Greater Treant) when the double dies.
- The Tempest Double does not gain any experience like heroes usually do, so it does not leech experience.
Item Interactions
- The double has its own, independent inventory, carrying the same item as the original Arc Warden does.
- On each cast, the double's inventory gets updated and adapted to that of Arc Warden. This also sets all charges of charge-based spells to match the charges on Arc Warden, no matter how many the double had left the last time it was summoned.
- The double can neither pick up, nor drop any items. It cannot be given items by allies or Arc Warden directly either.
- It can be given an
Observer Ward and 
Sentry Ward, since their sharing mechanics work different (CTRL override) than those of other items.
- It can be given an
- Since the double gets re-summoned on each cast, all its item (and ability) cooldowns do not reset, just like how heroes do not get their cooldowns reset as they respawn.
- The double does not copy the following items:
Aegis of the Immortal
Animal Courier
Cheese
Divine Rapier
Flying Courier
Gem of True Sight
Observer and Sentry Wards
Smoke of Deceit
Tome of Knowledge- Any muted item which Arc Warden has in its inventory (allied and enemy items alike).
- All other items are copied, although some have a slightly altered effect. Shareable items (e.g.
Town Portal Scroll or 
Perseverance) are copied. 
Bloodstone does not apply the area heal upon the double's death. Besides that, the item works normally for the double, meaning it does gain charges, and the double can use Pocket Deny.
Hand of Midas can be used by the double. Using Transmute grants the gold and experience to the main hero.- If Arc Warden has bottled a rune, the double gets a full
Bottle instead and does not copy the rune. The double can also not put runes into its Bottle, and cannot pick up runes in general. - If
Radiance, 
Ring of Aquila or 
Ring of Basilius are toggled off upon summoning the double, they are also toggled off on the double. The toggle status gets copied. - The same applies to
Power Treads. The double copies whichever attribute the main hero had selected. 
Black King Bar gets its "level" also copied. If the main hero's Black King Bar is at 6 seconds duration, so is the double's Black King Bar.- When having a unit dominated with
Helm of the Dominator, the unit does not die when the double expires. However, it does die as soon as the double gets re-summoned. - Moon Shard cannot be consumed by the double itself, but can still be copied as a standalone item or as a buff, if the main Arc Warden carries the buff.
- Refresher Orb is always on cooldown for the double, so it cannot refresh
Tempest Double, but still can benefit from its stats.
Recommend Item
Slippers of Agility and a 
Circlet give the stats Arc Warden needs early on and can later be built into a 
Wraith Band.
Tango gives Arc Warden sustain in lane and a slight damage buff to make last hitting easier.
Early Game:
Boots of Speed improves Arc Warden's mediocre movement speed and gives him some form of escape from enemies.
Ring of Aquila gives stats and a source of pushing at a cheap price. Remember to keep the aura turned off when you're not trying to push the lane.
Enchanted Mango can give Arc Warden a constant source of cheap mana if you don't consume it and instead let the Tempest Double use it on you whenever you need the mana.
Core Items:
Hand of Midas is essential on Warden as otherwise he could not farm at all. Keep track of it's CD on Tempest Double to know when optimal times to call it are.
Boots of Travel gives Warden map wide presence for fighting, pushing, and farming.
Magic Wand is a good way to heal back up some health and some mana. It also makes use of the circlet and branches bought earlier and frees up inventory space.
Bottle is a great pick up on Arc Warden. Not only does it help with sustaining and manage runes, it also gets its effectiveness almost doubled when used by his Tempest Double.
Power Treads are an alternative to Travels if you need to fight early on. These can later be sold for Travels anyway.
Arcane Boots helps Arc Warden sustain the mana cost of his spells. Spark Wraith being very spammable can quickly deplete his mana pool. Compared to other boots, Arcane boots are also the most effective boots for the Tempest Double (besides Boots of Travel), doubling the amount of mana restored to the team.
Necronomicon is very effective on Arc Warden as well, again, thanks to his ultimate. He can have 2 sets of Necronomicon units up at the same time, since the units summoned by the double are independent and do not replace the units summoned by the main Zet. Necronomicon is an essential item for a pushing Arc Warden.
Situational Items:
Scythe of Vyse is a great disable and immensely boosts Arc Warden's mana and mana regeneration, eliminating mana problems which may occur. The Hex duration can also be effectively doubled with the help of a Double.
Mjollnir buffs both yours and your Tempest Double's attack speed as well as punishing enemies who attack either.
Diffusal Blade gives a purge, and it improves Warden's dreadful agility gain.
Desolator helps with both pushing towers and tearing down foes, all at an efficient price Warden can easily reach.
Black King Bar helps against disables or nukers if such are problems. It can also be used to send in the double in fights and staying back in safety with the main Arc Warden. The Double can use Avatar, but its duration is the same as the one of the main Zet's Black King Bar.
Maelstrom improves Warden's farming and pushing and can later build into 
Mjollnir.
Hurricane Pike is an alternative to 
Blink Dagger for a more offensive Warden. It lets him stay in the back with the increased range from it, and gives him an escape that, if used by Tempest Double as well, can effectively double the distance traveled.
Eye of Skadi is a luxury item on Warden that gives him all the stats he needs and another Black King Bar piercing slow. It does not, however, stack with 
Desolator.
Satanic is another luxury item that can be considered. It improves his rather frail nature and stacks fully with 
Eye of Skadi, but it does not stack with Desolator either.
Orchid Malevolence into 
Bloodthorn gives Warden more utility and a huge dps increase with Bloodthorn's crit that works with anyone on the team, including the double. It gives true strike as well for those pesky heroes with evasion.
Dagon is great when focusing on picking off heroes. Dagon itself already does a lot of burst damage. Doubling that with a Tempest Double, combined with the rather high damage of Arc Warden's other spells, this item can help to deal with even very tanky foes. Throwing in an 
Ethereal Blade can turn Arc Warden into one of the strongest nukers.
Moon Shard makes Arc Warden attack extremely fast when combined with Magnetic Field. When consumed, the Tempest Double also gains the permanent buff.
Daedalus can be good on Arc Warden for the same reason why Butterfly can be: it turns him into a strong hitter in the later phases of the game. Although Daedalus is chance based, Zet can still constantly deliver crits thanks to the enormous attack speed boost provided by Magnetic Field. Butterfly should be acquired before a Daedalus, to first get some attack damage and more speed first, to make critical strikes more effective.
Monkey King Bar is a great alternative to Daedalus when dealing with evasive enemies. Also thanks to its already high chance to interrupt an enemy with its mini-bash, it can even slow down an enemy heavily when attacking it with the Double as well, due to the amount of mini-bashes from 2 heroes attacking it with Monkey King Bar. The chances to quickly interrupt an enemy's channeling spells is very high.
Manta Style is a great item for pushes, as Arc Warden can have 4 illusions thanks to the Double. Just like with Necronomicon, the double's and the original's Manta Style are independent from and do not replace each other. The illusions also benefit from Magnetic Field's evasion, making them more resistance against physical attacks. They do not get the attack speed bonus, though.* 
Arcane Boots should be the go to boots for a Support Warden. With Tempest Double, you can replenish 270 mana to heroes nearby, which can be enough to have them use a team fight changing ult.
Urn of Shadows can give tons of healing if it's mainly Tempest Double using it, or even heal multiple allies at once.
Pipe of Insight should be considered over 
Mekansm on a support Warden, as you can apply the spell block twice in a fight, while you can only heal with Mek once every 35 seconds, rendering the second usage useless.
Butterfly can turn Arc Warden into a heavy hitter. His main attribute is still agility, so he benefits a lot from its stats. The Tempest Double has no attack damage penalties like most illusions do, since it is not an illusion, so it can greatly increase Arc Warden's overall damage output. Arc Warden's 2 damaging spells deal both magical damage and do not scale. A Butterfly helps him keep on doing damage to the enemy in the late game. The attack damage he gets from the item is also great for pushing and synergises very well with Magnetic Field.
Drum of Endurance can effectively have infinite charges if usage of the charges is restricted to the Double only, or give a charge twice as long with both the Double and main hero using it after the current charge duration ends.
Rod of Atos is a cheap utilty item for a support Warden that can keep a foe slowed for twice as long, or even slow 2 people down so they can't escape as quickly.
Shiva's Guard provides some protection against carries as it increases armor and slows their attacks passively. The active ability is also great for pushes. Although the aura does not stack when creating a Double, two Arctic Blasts also deal a decent amount of damage in fights.
Sumber: http://dota2.gamepedia.com/
