Defiler

Skill Build
1 – Wave of Death
2 – Grave Silence
3 – Wave of Death
4 – Power in Death
5 – Wave of Death
6 – Unholy Expulsion
7 – Wave of Death
8 – Power in Death
9 – Power in Death
10 – Power in Death
11 – Unholy Expulsion
12 – Grave Silence
13 – Grave Silence
14 – Grave Silence
15 – Stats
16 – Unholy Expulsion
17 – Stats+

Justification / Modifications:
Grave Silence is taken at level two as it is very useful both defensive and offensive. For example to kill evasive heroes like Scout or Magebane.
The rest is straightforward.

Lane Starting Items:
1x Runes of the Blight, 1x Healing Potion, 1x Mana Potion, 1x Minor Totem, 2x Mark of the Novice

Core:
Bottle >> Ghost Marchers >> Power Supply >> Sacrificial Stone

I consider Sacrificial Stone core on Defiler as this is what lets her scale into lategame. She is such a nice farmer and if properly played can get her Sac Stone relatively early. If no one on your team gets Plated Greaves or if you are facing massive armor reduction heroes, consider Plated Greaves instead of Ghost Marchers.
Ghost Marchers make her the fastest thing on Newerth!

After Core:

Alternative Items:
– Storm Spirit: Can be gotten directly after core or even earlier. Use it on yourself while your ultimate is running for maximum effect.
– Void Talisman: Lategame against melee carries. Use when your ult is on.

Information:
Roles: Pusher, Nuker, Tank, (Semi-Carry)
Prefered Lane: Mid
Difficulty: 4 – Hard
Farming capabilities: 5 – Excellent
Item dependancy: 4 – Heavy (For Semi-Carrying at least)
Power:
– Early Game / Lane Control: 4 – Strong (Dominant Nukes)
– Mid Game / Ganks: 4 – Strong (Insane Pushing Power)
– Late Game / Team Fights: 3 – Medium (can tank with ult up)

30-Seconds-Guide:
– Your Ultimate is the single best pushing spell in the game. Use it to take down towers starting as early as possible. (You will need your teams support for this tho).
– Wave of Death is a spammable farming nuke, use it to harass and farm up.
– Silence is very very important in teamfights. Never forget to use it!
– If fighting evasive heroes with blinks/vanish/etc you maybe wanna save your silence for when they go low HP to ensure a kill.
– With your ultimate up you are almost untouchable in the mid game. You can take most 1vs1 and even 1vs2 battles. Just make sure you use it before you are at 20% hp.

Counters:
– Her Ultimate is Physical damage while her Wave of Death is Magical. This means Magic Armor is not as effective against her as you might think. Don’t bother getting it just for her.
– When she has her ultimate up and you are alone: RUN!
– Deny her Rune Control in Mid, this will make the harass much more bearable.