The Sisters of The Veil, will crit you frail

Introduction

Phantom Assassin is a very hard carry that excels in chasing, ganking and escaping.
She needs items really badly in order to make her ultimate effective, but if the farm-phase succeeds, she will nuke opponents with her auto-attacks, often killing them with a SINGLE BLOW.
In this guide I will go through my experiences and some alternate builds with Phantom Assassin I have gotten quite a lot of success with, and there will surely be disagreement, so I will try to justify the items the best I can.
I have added an conclusion in each justification, for the lazy or know-it-all types.

This is my first guide, I have played the game for about 2 months and english is not my native language, yada yada yada. So please be nice :)

There will be mathcraft in this guide and from my experience, most people hate math, so I have tried to keep it at a minimum on the guide and added a Mathcraft section for those who are truly interested in the reasoning behind, ehm... everything!

Stroke of Grace - Lore

Through a process of divination, children are selected for upbringing by the Sisters of the Veil, an order that considers assassination a sacred part of the natural order. The Veiled Sisters identify targets through meditation and oracular utterances. They accept no contracts, and never seem to pursue targets for political or mercenary reasons. Their killings bear no relation to any recognizable agenda, and can seem to be completely random: A figure of great power is no more likely to be eliminated than a peasant or a well digger. Whatever pattern the killings may contain, it is known only to them. They treat their victims as sacrifices, and death at their hand is considered an honor. Raised with no identity except that of their order, any Phantom Assassin can take the place of any other; their number is not known. Perhaps there are many, perhaps there are few. Nothing is known of what lies under the Phantom Veil. Except that this one, from time to time, when none are near enough to hear, is known to stir her veils with the forbidden whisper of her own name: Mortred.

Pros and Cons

Pros

Cons

Not that hard to play Good stat gain Scales in both extreme damage and EHP late game

Frail against casters Not a strong early-gamer Easily countered by damage return

Skillz that killz

Stifling Dagger

Type: Targets:

Active Enemy Units

Deals minor pure damage and slows the enemy unit's movement speed. Deals half damage to heroes.

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This will help you out a lot, it can be used to last hit due to its high pure damage, and since it has such a long range, it can be used to cancel Healing salves and Clarities.
It has also great uses with the ability to slow and enemy chasing you or if one of your team-mates comes to gank in your lane, you can slow the specified target, which often leads to a succesful gank.
This should be maxed first since the mana-cost will go down by a significant amount, so you are able to spam this.

Phantom Strike

Type: Targets:

Active Units

Teleports to a unit, friendly or enemy, and grants bonus attack speed while attacking if it's an enemy unit.

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This is what makes Phantom Assassin such a great chaser and escaper.
And you can save yourself the worry about buying any Attack speed, since this skill will do it for you.
An obvious combo is Stifling Dagger --> Phantom Strike --> Auto-attack. You will this way get a lot of hits on both fighting enemies and fleeing enemies, nobody will be able to escape you. It is great for kill-stealing, which is totally okay, fantastic in fact, since you need to earn gold in order to be effective. If you have a well coordinated team, it will serve as a reliable escape mechanism or if you are on your own, Helm of the Dominator is a great combo since you can blink to your dominated creep.

Blur

Type: Targets:

Passive N/A

The Phantom Assassin becomes hard to see by blurring her body and disappearing from the enemy minimap when near enemy heroes. Some enemy attacks miss.

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Will cause a lot of confusion for your enemies, and you can gank easily in pubs since people usually don't call miss and they can't see on the mini-map if you are there or not. In teamfights you will be pretty hard to get track on with your transparency and Phantom Striking from one opponent to the other. It is going to make you nearly immune to auto-attacks (same evasion percentage as Butterfly at highest level) and combined with a BKB, you will become invincible.
Take an early point in it, to confuse and become really survivable in lane.
Max last as it does not scale as well as your other abilities, if the enemies auto-attack damage is pitiful, get stats instead and max from level 22 - 25

Coup de Grce

Type: Targets:

Passive N/A

Phantom Assassin refines her combat abilities, gaining a chance of delivering a devastating critical strike to enemy units

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A free (and better) Daedalus, how you might ask?
See:
Daedalus gives you 25% to crit for 240% of your damage, that means the other 75% you are going to do normal damage (obviously), so average increase in damage is:
(240% * 25% + 100% * 75%)-100% = 35% damage increase.

Coup the Grace gives:
Level 1 = (250%*15%+100%*85%)-100% = 22.5% damage increase (meh, OK I guess)
Level 2 = (350%*15%+100%*85%)-100% = 37.5% damage increase (already surpassed).
Level 3 = (450%*15%+100%*85%)-100% = 52.5% damage increase (BR0K3N H3RO, PL0x N3Rf)

Item justification 1 - Starting into early game

Basic regen will help you stay in lane, 2xIron Branches to give you a bit of strength and last hit potential and 2x[Slippers of Agility] that is a great early replacement for a Quelling Blade and you should build it into a Poorman's Shield, since your opponents are not going to be nice to you, then you can either go for the Magic Wand if you are against ability-spamming opponents, otherwise go for Tranquil Boots which is an amazing item, it will also help sustain the Armlet of Mordiggian you will be rushing afterwards, which brings us to my next section:

Effective starting items that will give you good stats and last-hitting superiority, all items can easily upgraded so that nothing goes to waste. The early-game build offers a lot of survivability and sustain for the armlet.

Item justification 2 - Is that a f******* Armlet?

Yes and to be honest, you shouldn't hate on the Armlet, it is a very potential item for any auto-attacker. Espicially Phantom Assassin. The reason being that I choose Armlet of Mordiggian is that it gives you the ability to at least kill-steal early on, and you actually feel sort of safe from ganks since your gankers either have 475 extra HP and 5 armor to chunk through or 40 damage and 0.25 attack-speed to deal with. There might be a argument to rush Battle Fury, but I have quite frankly never been able to, and unless your team knows how to distract them I would not recommend it. Armlet of Mordiggian offers everything Phantom Assassin needs, and it allows her to be aggressive early on, it also solves the HP/armor/evasion balance, since she will naturally get a lot of armor and have high evasion, but a little HP to make full use of it,
Armlet works wonders.

Item Justification 3 - Desolator vs. Battle Fury

Tower Pushing Insane DPS increase for both you and your allies

Lane Pushing Insane GPM just for you

Choosing between these two items depends on what your team needs and what strategy your team is going for. If your team lacks in the ability to clear creep-waves, then Battle Fury can do the job, while if your team lacks the ability to take towers down quickly, then you should take Desolator
Examples of heroes that are good at lane pushing:
Pugna, Tinker, Shadow Fiend, Invoker, Death Prophet and many more.

Examples of heroes that are good at Tower Pushing:
Shadow Shaman, Lone Druid, Death Prophet, Nature's Prophet and many more.


Battle Fury is a very common choice on Phantom Assassin, and for good reasons, she is a hard carry after all and so she needs all the GPM she can get, but in some games you will notice that DPS equals GPM, and by that I mean if you have the ability to take towers down quickly or 1 hit a squishy enemy lineup in a quick succession (and of course, steal kills from your team-mates), then you will see that Desolator in some instances will make both your Hard-Carry potential get revealed a lot earlier, but also make your GPM higher than Battle Fury ever could. If we look at the fighting potential only, the cleave from Battle Fury can damage multiple opponents and cleave ignores armor! While Desolator's armor debuff will make your whole team able to kill both towers and chosen opponents earlier. The regen from Battle Fury is good, but not really that important, you can recover faster from a prolonged team-fight where you had Armlet toggled on all the time, but this problem will be solved as soon as you get lifesteal anyway and an over-aggressive tendency have never benefited a hard-carry
But on a bright note Desolator should not be taken if your team already have a Desolator - carrier, due to the armor debuff will not stack at all.

It is a situational pick, if you are interested in seeing how much DPS you can actually get from Desolator, then go to the Mathcraft section.
You should definitely not aim for both, as they both will taper off in efficiency if they are gotten any later.

If you do get Battle Fury, get this

Just get it, it will speed up your farm insanely much to be able to 1 hit creeps is too good to pass up. Just get rid of your now useless Magic Wand so you always have a spot for the TP.

Item Justification 4 - HotD vs. Vladmir's Offering

Get a free pet :D Great late-game potential Lifesteal

Regen Pushing Lifesteal

I am going to make this one short, since it depends on your previous strategy and prior picks.
,,So which one?" you ask.
Helm of the Dominator is a super-special-awesome choice if you went Battle Fury, the reason being that with your new acquired pet, you can make it stack camps for you! Preferably the ancient camps, as they give you the most XP and gold. Or if you are are one of those annoying-to-deal-with micro-management masters, you can even dominate an Alpha Wolf (the biggest Wolf you can find in the forest) and make your DPS even more insane. Also if you have picked Battle Fury you do not need the regen from Vladmir's Offering and since you kill off enemy creep waves so quickly: Your creeps will even not need the armor or lifesteal.
And the best of it all is that you can make it into a Satanic to make you invincible.
While the opposite applies to Desolator:
Since you lack regen, you should pick Vladmir's Offering it will not only give you lifesteal, little bit of damage and solve your regen issues, it will also make you into a formidable pusher: Your aura gives allied creeps armor and lifesteal, so they are able to survive with pretty much all of their HP intact before reaching the enemy tower, and when they begin hitting the enemy tower, you will place the Desolator debuff and the tower will simply melt.
Aggressive playstyle/Pushing: Desolator + Vladmir's Offering
Late-game strategy/Farming: Battle Fury + Helm of the Dominator

Item Justification 5 - Phase Boots vs. Power Treads

Speed Boost Damage Increase

Stat manipulation Attack-speed increase

The speed boost from Phase Boots is pretty useless on a hero that can both slow and blink to the opponent, so it will only be useful in escape situation, which is most often you blinking to an ally, but if you are unlucky to find yourself in a lonely situation, where the only company is your enemies hunting you, then you have an ability to outrun them.
However the stat manipulation is awesome, you will never have mana-issues, which could potentially save you in sticky situations, and the survivability it offers (19HP * 8 = 152HP) is much needed on a hero as squishy as Phantom Assassin.


The damage increase from Phase Boots is quite noticable, espicially if you take Coup de Grace into the equation, it will definitely boost your damage potential early-mid game. However the Attack-speed which is quite a lot (30%) gives you a higher chance to crit, which is great, and that is the only piece of attack-speed Phantom Assassin would ever need, and as your damage increases, Power Treads will easily outclass the DPS given from Phase Boots.
There is a more in-depth conclusion on this topic in the Mathcraft section, but in short, Power Treads will give you a higher DPS than Phase Boots in the long run.


It comes down to skill-level and personal preference, if you are a Tread-switch Master, then you should go for Power Treads, while on the other hand if you are on those who think Skeleton King is a hero too complicated to play, then go for Phase Boots.

Friends and Foes

Friends

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Friends of Phantom Assassin is:



Armor-reducers/size]

Especially if you go Desolator yourself

Disablers and Slowers

Windrunner

• He can heal you so the armlet becomes even more favorable
• He usually goes Arcane Boots so you do not have to worry about mana that much
• With Repel you are going to be pretty aggressive with no chance of failure (except for the really hard counter yet to come).
  
  Foes

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  Foes of Phantom Assassin is:
  
  Disablers and Slowers
  
  
  Nukers
  
  
  Doom Bringer

  
  Doom Bringer
  
• His ultimate goes through BKB renders your passives completely useless so even with your Omnifriend, you will probably die.

From Mathcraft to Monsterkill

EHP is a rather complicated subject, but it has to do with how much actual physical damage it will take to reduce a units HP to 0.
In this we will need to calculate the following things: Evasion, HP and armor.
This guy will probably teach it better than I: Play Video /dota-2/item/armlet-of-mordiggian-76 If we take an example, if we have an enemy with 10 armor, that means he has an physical resistance on 37.5%, when he gets hit by the Desolator his armor will fall down to 4 (19.4% physical resistance), your teamates DPS will therefore also increase on that target, so (1-19.4%)/(1-37.5%) = 1.29 will be multiplied into each of your teammates DPS, which is obviously INSANE.

You see, DPS is actually what it says it is Damage per second, so to calculate this we need to know how many times a unit hits per second and how much damage each hit does on average. Generally this means that as a carry, you should strive for a balance between damage and attack-speed, and many PA players is just content with building raw damage after raw damage, when it means that they are lacking the ability to hit fast enough.
But here is the calculation of Helm of the Dominator and Battle Fury build at


Level 11:

Phase (With Phantom Strike) = (3.15*11+23+24+24+24+40+65)*(0.15*3.5+0.85)(1+1+3.15*0.11+0.23+0.25/1.7) = 879 DPS

Phase (Without Phantom Strike)=(3.15*11+23+24+24+24+40+65)*(0.15*3.5+0.85)(1+3.15*0.11+0.23+0.25/1.7) = 556 DPS

Treads (With Phantom Strike) = (3.15*11+23+24+24+40+65)*(0.15*3.5+0.85)(0.3+1+1+3.15*0.11+0.23+0.25/1.7) = 876 DPS

Treads (Without Phantom Strike) = (3.15*11+23+24+24+40+65)*(0.15*3.5+0.85)(0.3+1+3.15*0.11+0.23+0.25/1.7) = 586 DPS

level 25:

Phase (With Phantom Strike) = (3.15*25+23+2*10+24+24+24+40+65)*(0.15*4.5+0.85)
(1+1+3.15*0.25+0.23+0.2+0.25/1.7) = 1533 DPS

Phase (Without Phantom Strike) = (3.15*25+23+2*10+24+24+24+40+65)*(0.15*4.5+0.85)(1+3.15*0.25+0.23+0.2+0.25/1.7) = 1077 DPS

Treads (With Phantom Strike) = (3.15*25+23+2*10+24+24+40+65)*(0.15*4.5+0.85)
(0.3+1+1+3.15*0.25+0.23+0.2+0.25/1.7) = 1535 DPS

Treads (Without Phantom Strike) = (3.15*25+23+2*10+24+24+40+65)*(0.15*4.5+0.85)(0.3+1+3.15*0.25+0.23+0.2+0.25/1.7) = 1116 DPS

In conclusion, the utility and DPS of Power Treads outclasses Phase Boots, in mid-late game.

Shoutouts

Thanks to
Dr. Dre for teaching how to format
Numeta for making thought-provoking builds and pretty much inspired me to do this
To XvRogue for making great videos
And to the great dota-community (most of the time) with its open-mindedness and curiosity that have brought Dota come so far.