Dark Seer:
Introduction
Thought by some to be among the most cunning and manipulative among the Scourge's varied champions, the dark seer Ish'kafel, living in exile from his people, is also the most secretive, for he speaks to no one but the Lich King himself. His unconventional talents, which lie in augmenting himself and allies with a variety of both defensive and offensive supportive castings, are quite unusual and versatile, often capable of turning the tide of battle before it even starts.

The Dark Seer is a master of manipulating the positioning of allies and enemies and causing confusion in battle. His Vacuum ability drags all enemy units a wide area to a central location. This spell is very deadly when combined with allies who have strong area of effect spells. The Dark Seer's primary damage source is Ion Shell. When cast on an allied unit or the Dark Seer himself, Ion Shell continuously damages all adjacent enemies, making it the natural complement to Vacuum. Ion Shell is powerful when cast on allied melee heroes who like to be in the thick of the fight. To aid his allies and to make sure Ion Shell is in range, the Dark Seer uses Surge, a powerful spell that makes a target ally move at maximum speed for a short period of time. This ability is useful in any situation, and due to its low cooldown period and mana cost it can be cast quite frequently. The Dark Seer's final spell, Wall of Replica, summons a shimmering barrier which duplicates any enemy hero that passes through it, creating an illusion of him. Wall of Replica is great at causing a lot of confusion during large battles, especially combined with Vacuum. For players who like a more strategic playstyle and can quickly determine the flow of battle, the Dark Seer is a good choice.
Skill info

Vacuum

Creates an abyss upon a chosen parameter, pulling in and damaging foes in the area.

Ion Shell

Surrounds a target with energized spellwork, creating a shield that causes damage per second to enemy units who come in contact with it.

Surge

Floods a target with excess power giving it maximum speed for a brief period of time.

Wall of Replica

Raises a wall out of pure mana across the landscape. Enemy heroes who attempt to pass through it will take damage and have images of themselves emerge from the wall to serve under the Dark Seer until the wall's duration is up.

Skill build:

Level 1 - Surge Level 10 - Surge
Level 2 - Vacuum Level 11 - Surge
Level 3 - Ion Shell Level 12 - Surge
Level 4 - Vacuum Level 13 - Wall of Replica
Level 5 - Vacuum Level 14 - Wall of Replica
Level 6 - Ion Shell Level 15 - Stats
Level 7 - Vacuum Level 16 - Wall of Replica
Level 8 - Ion Shell Level 17 - Stats
Level 9 - Ion Shell Level 18+ - Stats

* If you prefer harassing, max Ion Shell first instead.
If you went to a solo lane, take Ion Shell and Surge in between until you maxed Ion Shell, after Ion Shell max Vacuum.