I was playing HNTR AoI, and by the time I got to the Cybie I was short on cells, but I had Intuition and rockets, so I grabbed the napalm launcher and started firing towards his position. After a few shots I noticed that he wasn't moving anymore. So I came closer and he wasn't even shooting.
After that he was just staying still in the large pool of lava outside my FOV while I was gunning him down to get my free buggy Cyberdemon's head.
Here's the mortem, just in case.
--------------------------------------------------------------
DoomRL (v.0.9.9.3) roguelike post-mortem character dump
--------------------------------------------------------------
Dash, level 10 Cacodemon 2nd Lieutenant, defeated the Cyberdemon
on level 25 of the Phobos base.
He survived 152548 turns and scored 99251 points.
He played for 3 hours, 5 minutes and 44 seconds.
He didn't like it too rough.
He killed 580 out of 649 hellspawn. (89%)
He was an Angel of Impatience!
He saved himself 4 times.
-- Special levels --------------------------------------------
Levels generated : 8
Levels visited : 6
Levels completed : 4
-- Awards ----------------------------------------------------
Cyberdemon's Head
UAC Star (bronze cluster)
Hell Champion Medal
Hell Armorer Badge
Eagerness Silver Badge
-- Graveyard -------------------------------------------------
###########################################################
#.....................................................=====
#.....................................................=====
#......................................................===.
#..........................................................
#........===##...###.....................=====..........###
#.......=====#...###...===##....=======.=======.........###
#.......=====#...###..======...================.........###
#.......=====.........=======..================............
#........===..........=======..=========.======............
#.............###......=====....=======....===.............
#.............###..........X..................###..........
#.............###.............................###..........
#.............................................###..........
#...................................###....................
#....###...................###......###....................
#....###...................###......###....................
#....###...................###.............................
#..........................................................
###########################################################
-- Statistics ------------------------------------------------
Health 83/50 Experience 49522/10
ToHit Ranged +4 ToHit Melee +4 ToDmg Ranged +0 ToDmg Melee +0
-- Traits ----------------------------------------------------
Tough as nails (Level 3)
Son of a gun (Level 2)
Eagle Eye (Level 2)
Intuition (Level 2)
Badass (Level 1)
TaN->EE->TaN->Bad->EE->Int->Int->TaN->SoG->SoG->
-- Equipment -------------------------------------------------
[a] [ Armor ] plate armor [8]
[b] [ Weapon ] modified rocket launcher (6d6) [0/1] (T1)
[c] [ Boots ] tactical boots [1/1] (100%)
[d] [ Prepared ] modified plasma rifle (1d8)x6 [0/40] (P1)
-- Inventory -------------------------------------------------
[a] modified combat shotgun (7d3) [6/6] (B1)
[b] gatling gun (1d7)x6 [0/52]
[c] modified tristar blaster (4d6)x3 [0/45] (P1)
[d] nuclear BFG 9000 (8d8) [2/40]
[e] modified napalm launcher (7d8) [1/1] (P1)
[f] modified BFG 9000 (10d8) [0/130] (B1)
[g] modified red armor [6/6] (100%) (P)
[h] shotgun shell (x41)
[i] shotgun shell (x50)
[j] shotgun shell (x50)
[k] rocket (x3)
-- Kills -----------------------------------------------------
89 former humans
83 former sergeants
28 former captains
73 imps
70 demons
106 lost souls
31 cacodemons
16 barons of hell
1 Cyberdemon
26 hell knights
15 arachnotrons
4 former commandos
7 pain elementals
12 arch-viles
9 mancubi
6 revenants
2 bruiser brothers
1 shambler
1 Arena Master
-- History ---------------------------------------------------
He started his journey on the surface of Phobos.
On level 2 he entered Hell's Arena.
He left the Arena as a champion!
On level 6 he stormed the Chained Court.
He defeated the Hell Arena Master!
On level 10 he entered Hell's Armory.
On level 10 he assembled a gatling gun!
On level 10 he assembled a tactical boots!
On level 10 he assembled a plate armor!
He destroyed the evil within and reaped the rewards!
On level 13 he ventured into the Halls of Carnage.
On level 15 he encountered the Phobos Hellgate.
On level 19 he entered the Vaults.
He managed to scavenge a part of the Vaults treasures.
On level 22 he was foolish enough to enter the Mortuary!
He managed to escape from the Mortuary!
Then at last he found Phobos Arena!
On level 25 he finally defeated the Cyberdemon.
-- Messages --------------------------------------------------
Fire -- Choose target...
You see : out of vision
Fire -- Choose target...
You see : out of vision
Fire -- Choose target...
You see : out of vision
Fire -- Choose target...
You see : out of vision
You swap your weapon.
Fire -- Choose target...
You see : out of vision
You reload the rocket launcher with rocket.
Fire -- Choose target...
You see : out of vision
You hear the scream of a freed soul! You feel relatively safe now.
Congratulations! You defeated the Cyberdemon! Press <Enter>...
-- General ---------------------------------------------------
Before him 76 brave souls have ventured into Phobos:
67 of those were killed.
1 of those was killed by something unknown.
And 3 couldn't handle the stress and committed a stupid suicide.
Some rumours though, say that the Cyberdemon was killed already!
Is he immortal? 5 souls claim to have killed him...
5 killed the bastard and survived.
--------------------------------------------------------------