Vortex

Spell effects
Vortex opens a small purple and black portal on the ground that exerts a weak pull on nearby units. If no units are sucked in, the vortex fails to sustain itself and vanishes within three or four seconds. Once a unit is sucked into the vortex, however, it is utterly destroyed, and the mass of the destroyed unit contributes to increasing the size, force, and duration of the vortex. To provide the vortex with a larger mass, drop spells into it that include earth, use Raise Dead to send waves of shambling fodder into its maw, or employ Push or Tornado to fling enemies into it.

Achievements
The following achievement requires the use of Vortex:

Pros

 * Can "one-shot" whole armies and even most bosses. If something goes inside, it will never come back (unless it is a wizard with someone to cast Revive).
 * Utterly destroys its target, rather than dealing damage
 * Appears in a mostly predictable location
 * Becomes more powerful as enemies are slurped inside
 * Appears to pull the caster less than it pulls enemies
 * If it starts to suck you, it's possible to escape using Haste (more "horsepower" in wizard's legs), Teleport or Nullify Magicks.
 * Can be "fed" with spells containing or  to increase its range and duration.
 * Looks bizarre and fascinating. In fact, it's a black hole.
 * One of the best magicks in challenge mode. The only ones even close are Summon Elemental, Haste, Conflagration, Napalm, and Thunder Bolt.

Cons

 * Long casting time
 * Can easily kill the caster, allies and minions
 * Loot from killed enemies is also destroyed
 * Most bosses are immune (But if you cast Vortex directly on them it will kill any boss that moves, like Ygg, Jotunn, Warlock, Khan, The Aristocrats, Vlad, Death, and Assatur.)
 * Can be removed by casting Nullify, which has a much faster cast time.