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  APOCALYPSE
  © Games Workshop Limited 2008. Games Workshop, Warhammer, Warhammer 40,000, Apocalypse are ©, TM and/or ® Games Workshop Limited 2008. All rights reserved.
  The Thousand Sons were once counted amongst the most
  loyal of the Emperor’s Legions, but that all ended when
  their Primarch, Magnus the Red, attempted to use
  forbidden magics to warn the Emperor of Horus’s treachery.
  Exiled from the Imperium by the Emperor, the Thousand
  Sons now reside in a place of twisted sorcery from where
  they travel out into the galaxy to gather slaves for their
  magical experiments. 
  A Thousand Sons Sorcerer is capable of unleashing a
  powerful psychic attack known as the Storm of Change. In
  order for the power to work the Sorcerer must be
  supported by a coven of Aspiring Sorcerers who will help
  him perform the ritual of summoning. The Coven is very
  vulnerable to attack while they are performing the ritual,
  and so they will usually be protected by units of Thousand
  Sons Chaos Terminators.  
  When the ritual of summoning reaches its climax, one or
  more of the Aspiring Sorcerers are temporarily drained of
  all their psychic energy, which is then redirected at the
  enemy in the form of a devastating psychic attack. The
  drained Aspiring Sorcerer collapses and will not recover
  until days later. 
  THOUSAND SONS WARCOVEN
  POINTS: 200 + MODELS
  AHRIMAN
  TERMINATORS
  CHOSEN
  FORMATION:
  1 Thousand Sons Chaos Space Marine Sorcerer or Ahriman
  1 Thousand Sons Chosen Chaos Space Marine Squad
  0-3 Thousand Sons Chaos Terminator Squads
  SPECIAL OPTIONS & UPGRADES
  All models in the Warcoven are considered to have the Mark
  of Tzeentch for free.
  All models in the Chosen Squad are Aspiring Sorcerers and
  cost 60 points each. They all have the Inferno Bolts special
  rule, and may take psychic powers from the list in the
  Thousand Sons troops entry in Codex: Chaos Space Marines.
  Thousand Sons Chaos Terminator Squads are Fearless, Slow
  and Purposeful, and their combi-bolters fire Inferno Bolts.
  They must include one (but only one!) Terminator Champion,
  who costs +30 points rather than +10 points as would
  normally be the case. In addition to his other abilities he is an
  Aspiring Sorcerer, and therefore benefits from the Sorcerer
  Commands and Inferno Bolts special rules, and may take
  psychic powers from the list in the Thousand Sons troops
  entry in Codex: Chaos Space Marines. The Aspiring Sorcerer
  is the only model in the squad who is allowed to take any
  other options.
  SPECIAL RULES
  If Ahriman or the Chaos Sorcerer leading the Warcoven joins
  the Chosen Squad, then they may choose to drain one or
  more members of the squad in order to use the Storm of
  Change psychic power. The unit may not be engaged in close
  combat at the time, and may not move or shoot on the turn
  the model is drained other than to unleash the power; they
  are too busy performing the ritual required to power the
  spell. The models that are drained are removed from play
  when the Storm of Change is unleashed – no save of any sort
  is allowed. The models do not count as casualties, however,
  and so no Morale check is required if 25% or more are the
  models in the unit are removed.
  Storm of Change: Storm of Change may be used in the
  model’s Shooting phase instead of using another ranged
  weapon. If the psychic test is successful then the Storm of
  Change counts as a weapon with the following profile:
  RANGE
  STR
  AP
  SPECIAL
  48"
  8
  1
  Apocalyptic Barrage (X)
  (X = number of models drained 
  that turn)
  
SOURCE: textdata/thevault/Warhammer/40k/1st-8th Editions (Prior)/5th Edition (2008)/Apocalypse Datasheets/40k 5e - Chaos Space Marines - Thousand Sons Warcoven.pdf