Kel'Thuzad by WikiGaming

Enemies who die near Kel'Thuzad will periodically drop Corpses for Kel'Thuzad. Additionally Kel'Thuzad can place Gravestones that will also periodically spawn Corpses for him to use.

Kel'Thuzad will turn all corpses in an area into Ghouls that will attack nearby enemies. Heroic corpses spawn two Ghouls instead of one. Ghouls will not become corpses upon death. Kel'Thuzad can control the Ghouls with Q. Ghouls last 30 seconds.
15 sec cooldown.

Kel'Thuzad turns all corpses within a target area into an Abomination. The Abomination Gets stronger for each Corpse that is used to make it. Kel'Thuzad can control the Abomination with W. Abominations last 30 seconds.
45 sec cooldown.

Passively increases Kel'Thuzad's mana regeneration rate.
Kel'Thuzad can instantly kill a FRIENDLY minion and instantly regenerate 60 mana.
10 sec cooldown.

Kel'Thuzad Creates an area of Blighted Land that drains the life of all enemies within it's radius for 15 Seconds.  Enemies within take a total of 4% of their Maximum HP Per Second. This effect is Cut in Half for Structures. 
150 sec cooldown.

Kel'Thuzad Summons a powerful Frost Wyrm to a target location that deals large AOE damage and Has a reposition ability and can be targeted to an enemy. Lasts 20 seconds.
120 sec cooldown.