TEXT: BATTLEFIELD
  This scenario uses the battlefield set up guidelines, as 
  described on page 21 of Gang War, and may either 
  be a Zone Mortalis or a Sector Mechanicus battlefield.
  CREWS
  This scenario uses the standard rules for choosing a 
  crew, as described on page 22 of Gang War. Players 
  use Random Selection (D3+7) to choose their crew.
  DEPLOYMENT
  This scenario uses the standard rules for deployment 
  from page 22 of Gang War.
  TACTICS CARDS
  Each player may choose two Gang Tactics cards. If the 
  total Credits value of one player’s fighters is less than 
  their opponent's then they may select an additional 
  card for each full 100 credits of difference.
  MONSTER HUNT
  A bounty has been posted for a massive underhive beast.
  SPECIAL RULE: THE SUMP HORROR!
  The gangs are trying to bag a massive Sump Horror (as well as scrag each other), though first they must 
  flush the creature out. The Sump Horror is attracted to wounded prey. Whenever a fighter suffers a Flesh 
  Wound or is Seriously Injured, the player whose fighter was injured places a Beast’s Lair marker (or similar 
  token) within D6" of their fighter. These markers follow all of the rules for the Beast’s Lair (see page 65 
  of the Necromunda: Underhive rulebook), with the exception that they cannot be targeted by Shooting 
  actions from more than 6" away.
  Once six markers have been destroyed, the Sump Horror will emerge. Replace the final destroyed marker 
  with a large token or appropriate model. The Sump Horror has the following profile:
  M 
  WS 
  BS 
  S 
  T 
  W 
  I 
  A 
  Ld 
  Cl 
  Wil 
  Int
  3" 
  5+ 
  6+ 
  7 
  6 
  8 
  4+ 
  4 
  9+ 
  2+ 
  6+ 
  12+
  The Sump Horror has a 5+ save, cannot be Pinned, and its attacks are Strength 7 and inflict 2 Damage 
  with a save modifier of -3. Coup de Grace actions cannot be taken against the monster. At the start of the 
  End phase of each round, the Sump Horror fights any fighters in base contact, or if there are no fighters in 
  base contact, it moves, or charges (if in range) toward the nearest fighter.
  
  ENDING THE BATTLE
  The battle ends when either the Sump Horror is killed 
  or one gang has no fighters left on the board.
  VICTORY (SKIRMISH ONLY)
  If the gang that killed the Sump Horror is the winner, 
  otherwise the scenario is a draw.
  REWARDS (CAMPAIGNS ONLY)
  CREDITS
  The gang that slew the Sump Horror can claim the 
  bounty and add 3D6x10 credits to its Stash.
  EXPERIENCE
  Each fighter that took part in the battle gains 1 
  Experience. Fighters gain an additional 1 Experience 
  if they destroyed a Beast’s Lair maker. The fighter that 
  deals the killing blow to the Sump Horror gains D6 
  Experience. In an Arbitrated scenario, fighters that 
  send a monster Out of Action gain D3 Experience.
  REPUTATION
  Each gang that took part gains 1 Reputation. The 
  gang that killed the monster earns D6+1 Reputation.  
  ARBITRATING THE SCENARIO
  The Arbitrator controls the Sump Horror in an 
  Arbitrated scenario, and can place Beast’s Lair 
  markers anywhere on the board at the start of 
  the round. When the Sump Horror emerges, the 
  Arbitrator moves and fights with it at the start of 
  the End phase. Alternatively, the Arbitrator could 
  include multiple creatures (choosing appropriate 
  models and giving them profiles) instead of using 
  the Sump Horror rules. These creatures wander 
  the battlefield attacking gangers in the End 
  phase, with the gang that can take out the most 
  creatures being the winner.
  ABYSSAL BEAST
  DELTA-7 DEADZONES
  
SOURCE: textdata/thevault/Warhammer/40k/Necromunda/04 Necromunda - 3rd Edition (2017)/Expansion Characters and More/Monster Hunt.pdf