I am Lucas, and I have played Dota 2 for about a year now. I have discovered this website about 3 months, and it has helped me a lot. This is my first guide, one for phantom assassin, so this might be not as detailed as you expect, but it is work in progress, so I will add to it about once a month.
So Phantom Assassin is a hard carry that is very adapting, and can play on any lane, even in the jungle/off-lane. She can go against almost any character 1v1, and with the correct items she can take on 3 - 4, and is very good in team fights with the correct items. But if she doesn't have enough farm, she will become a burden for the team, as she will get owned easily by high damage such as Ursa.
- It is really high burst damage
- Can almost kill any hero in 1v1
- Can get like 20 kills if played correctly
- Can only focus on 1 enemy hero at a time
- Has to farm a lot, and is very squishy at early game and mid game
- Cannot be played well by amateur players.
The fist skill you should max out is your Stifling Dagger, as it slows people and it deals some damage, and after you get your ultimate Coup De Grace, it has the same chance of activating, which does quite some damage as well.
The second skill you should max out is phantom strike, as it gives you a easy way to catch up to your enemy, but take note as because unlike queen of pain or anti-mage's blink, you can only blink to characters, no matter ally or enemy. So you cannot use it as escape very well.
The third skill Blur should be maxed out the last, because playing phantom assassin normally means blinking to and killing an enemy before he can land a hit on you. So it really isn't useful in the early/mid games. But in the late game when enemies can be a lot tankier, you can use the evasion from the skill to dodge some of the hits. You can also use it as a tool to see if any invisible heroes are nearby, as then your blur icon will vanish from the effect bar above your skills.
The fourth skill, your ultimate is Coup De Grace. It gives you a 15% chance to have a crit at 2.3 -> 3.4 -> 4.5 times damage. So if you max it out and get a crit, it would be at a devastating 1000 and something damage.