Death Knight Death Coil
Cost: Free
Mana: 100
Death Coil is a particularly potent variation of Touch of Darkness. by channeling the necromantic powers of the underworld through his ghoulish form, the Death Knight creates a field of dark energy that drains the life-force from any who come in contact with it.
Death Coil is an area effect spell much like Death and Decay. When cast, you will lose mana even if no unit gets hit by the Death Coil. This explains why Death Coil misses. What happens is you cast it on an area, and the enemy runs out of the area before it is cast. If you want to test this, just cast a Death Coil in the middle of water or something. You will see you lose all the magic points but nothing happens. If there were some Gryphons over the water, you would have Death Coiled them. But since no organic enemy was in that area, the spell was cast, the mana lost and nothing happened. This is exactly how other area effect spells like Exorcism and Death and Decay work.
Death Coil does two things. It totally misses as in you cast it nothing happens but the mana is taken away and also appears to miss but really doesn't. Take a look at this picture. As you can see Death Coil appears to miss but it doesn't.
When multiple enemies are hit by Death Coil, the damage is distributed between them all. So the more enemies, the less damage it does.
You have no control over which unit is hit by Death Coil when cast on a group of enemies. Cast Death Coil on a block of 9 Peons. Then with your Death Knight, try to cast a Death coil on a specific Peon. Impossible. So when trying to attack specific enemy units try to get them separated from a group. Combine Death Coil and one or more Axe Throwers for destroying Dragons and Gryphons. The Death Coil takes most of the Dragons health and the Axe Thrower will finish the job.
Cast a Death coil on a Sheep, Pig, Seal or Boar to heal your Death Knight 5 hit points. A waste of mana but it is funny.