Not too difficult given HMP and a few lucky levels where I was able to camp respawns for killcount(Hunter Gold wants 80%) and ammo drops. Opened with Intuition to be sure I could secure Mastermind safely, so I never quite managed to finish Shottyhead, but shotguns were my go-to for the entire game.
One more gold for the next skill rank, then maybe I'll look at more impressive challenges.
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 DoomRL (0.9.9.7) roguelike post-mortem character dump
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 Nathan, level 8 Arch-Vile Lt. Colonel Scout,
 defeated the Mastermind at the City of Dis.
 He survived 165684 turns and scored 65681 points. 
 He played for 50 minutes and 2 seconds. 
 He wasn't afraid to be hurt plenty.
 He killed 606 out of 658 hellspawn. (92%)
 He held his right to remain violent.
 He was an Angel of Darkness!
 He was also an Angel of Overconfidence!
-- Special levels --------------------------------------------
  Levels generated : 4
  Levels visited   : 0
  Levels completed : 0
-- Awards ----------------------------------------------------
  UAC Star (gold cluster)
  Hunter Silver Badge
  Hunter Gold Badge
-- Graveyard -------------------------------------------------
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-- Statistics ------------------------------------------------
  Health 30/50   Experience 25472/8
  ToHit Ranged +0  ToHit Melee +0  ToDmg Ranged +0  ToDmg Melee +0
-- Traits ----------------------------------------------------
  Class : Scout
    Finesse          (Level 1)
    Hellrunner       (Level 1)
    Reloader         (Level 2)
    Juggler          (Level 1)
    Intuition        (Level 2)
    Shottyman        (Level 1)
  Int->Int->Rel->Rel->SM->Fin->Jug->HR->
-- Equipment -------------------------------------------------
    [a] [ Armor      ]   blue armor [2/2] (171%) (B)
    [b] [ Weapon     ]   assault shotgun (7d3) [4/6]
    [c] [ Boots      ]   protective boots [2/2] (96%)
    [d] [ Prepared   ]   shell box (x92)
-- Inventory -------------------------------------------------
    [a] rocket launcher (6d6) [0/1]
    [b] plasma rifle (1d7)x6 [0/40]
    [c] shotgun shell (x50)
    [d] shotgun shell (x50)
    [e] shotgun shell (x50)
    [f] shotgun shell (x50)
    [g] shotgun shell (x32)
    [h] shotgun shell (x50)
    [i] large med-pack
    [j] phase device
    [k] homing phase device
    [l] thermonuclear bomb
    [m] shell box (x100)
-- Resistances -----------------------------------------------
    Acid       - internal 0%    torso 0%    feet 25%  
    Plasma     - internal 0%    torso 20%   feet 0%   
-- Kills -----------------------------------------------------
    7 former humans
    340 former sergeants
    46 former captains
    58 imps
    19 demons
    97 lost souls
    1 cacodemon
    5 hell knights
    14 barons of hell
    3 former commandos
    6 pain elementals
    6 revenants
    3 arch-viles
    1 Spider Mastermind
-- History ---------------------------------------------------
  He sounded the alarm on level 4!
  Level 5 blasted him with an unholy atmosphere!
  Then at last he found Dis!
  On level 8 he finally defeated the Mastermind.
-- Messages -------------------------------------------------- 
 You quickly reload the assault shotgun. 
 Fire -- Choose target... 
 You see : out of vision 
 Fire -- Choose target... 
 You see : a Spider Mastermind (almost dead) | floor | [ m ]ore 
 Targeting canceled. 
 Fire -- Choose target... 
 You see : out of vision 
 You quickly reload the assault shotgun. 
 Your assault shotgun is already loaded. 
 Fire -- Choose target... 
 You see : out of vision 
 Fire -- Choose target... 
 You see : out of vision 
 You hear the scream of a freed soul! Congratulations! You defeated the Spider 
 Mastermind! Press <Enter>... 
-- General --------------------------------------------------- 
 771 brave souls have ventured into Phobos:
 665 of those were killed.
 2 of those were killed by something unknown.
 45 didn't read the thermonuclear bomb manual.
 And 43 couldn't handle the stress and committed a stupid suicide.
 16 souls destroyed the Mastermind...
 1 sacrificed itself for the good of mankind.
 14 killed the bitch and survived.
 1 showed that it can outsmart Hell itself.
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