Thing type 408, Invincibility Monitor , is a monitor  that gives the player invincibility for 20 seconds upon its destruction, playing the invincibility music (INVINCgametypes  except for Match and CTF due to the Super form's inherent invincibility.
Checking the Ambush  flag turns this monitor into a Weak Random Monitor . This is not recommended however, because WRMs do not spawn Invincibility. Checking the Special  flag turns it into a Strong Random Monitor , out of which it may randomly respawn with a probability of 12.50%.
This Monitor type also comes in a gold variation, Thing Type 438, Invincibility Monitor (Respawn) , which will give the player the Invincibility powerup once popped, before respawning after about 3 seconds. Its only occurrence in-game is twice in Red Volcano Zone Act 1 .
 
  Object type  info –  MT_INVULN_BOX 
 
  
Thing type number 
408
TVIVA0  
  
Object type 
MT_INVULN_BOX
 
  
Sprite name prefix 
TVIV
 
  
SpawnState
 
S_INVULN_BOX
 
  
SeeState
 
S_NULL
 
  
SeeSound
 
sfx_None
 
  
AttackSound
 
sfx_None
 
  
PainState
 
S_INVULN_BOX
 
  
PainSound
 
sfx_None
 
  
MeleeState
 
S_NULL
 
  
MissileState
 
S_NULL
 
  
DeathState
 
S_BOX_POP1
 
  
XDeathState
 
S_NULL
 
  
DeathSound
 
sfx_pop
 
  
ActiveSound
 
sfx_None
 
  
RaiseState
 
S_NULL
 
  
SpawnHealth
 
1
 
  
ReactionTime
 
8
 
  
PainChance
 
0
 
  
Speed
 
1
 
  
Radius
 
18*FRACUNIT
 
  
Height
 
40*FRACUNIT
 
  
Display offset
 
0
 
  
Mass
 
100
 
  
Damage
 
MT_INVULN_ICON
 
  
Flags 
MF_SOLID|MF_SHOOTABLE|MF_MONITOR
 
  
States – MT_INVULN_BOX
  
State
 
Sprite prefix
 
Frame
 
Duration (tics)
 
Action 
Var 1
 
Var 2
 
Next state
  
S_INVULN_BOX
 
TVIV
 
A
 
2
 
none 
0
 
0
 
S_BOX_FLICKER
  
S_BOX_FLICKER
 
MSTV
 
A
 
1
 
none 
0
 
0
 
S_SPAWNSTATE
  
S_BOX_POP1
 
MSTV
 
B
 
4
 
A_MonitorPop 
0
 
0
 
S_BOX_POP2
  
S_BOX_POP2
 
MSTV
 
B
 
-1
 
none 
0
 
0
 
S_NULL
  
 
  Object type  info –  MT_INVULN_GOLDBOX 
 
  
Thing type number 
438
TVIVB0  
  
Object type 
MT_INVULN_GOLDBOX
 
  
Sprite name prefix 
TVIV
 
  
SpawnState
 
S_INVULN_GOLDBOX
 
  
SeeState
 
S_NULL
 
  
SeeSound
 
sfx_None
 
  
AttackSound
 
sfx_monton
 
  
PainState
 
S_INVULN_GOLDBOX
 
  
PainSound
 
sfx_None
 
  
MeleeState
 
S_NULL
 
  
MissileState
 
S_NULL
 
  
DeathState
 
S_GOLDBOX_OFF1
 
  
XDeathState
 
S_NULL
 
  
DeathSound
 
sfx_pop
 
  
ActiveSound
 
sfx_None
 
  
RaiseState
 
S_NULL
 
  
SpawnHealth
 
1
 
  
ReactionTime
 
8
 
  
PainChance
 
0
 
  
Speed
 
0
 
  
Radius
 
16*FRACUNIT
 
  
Height
 
32*FRACUNIT
 
  
Display offset
 
0
 
  
Mass
 
100
 
  
Damage
 
MT_INVULN_ICON
 
  
Flags 
MF_SOLID|MF_SHOOTABLE|MF_MONITOR|MF_GRENADEBOUNCE
 
  
States – MT_INVULN_GOLDBOX
  
State
 
Sprite prefix
 
Frame
 
Duration (tics)
 
Action 
Var 1
 
Var 2
 
Next state
  
S_INVULN_GOLDBOX
 
TVIV
 
B
 
2
 
none 
0
 
0
 
S_GOLDBOX_FLICKER
  
S_GOLDBOX_FLICKER
 
XLTV
 
A
 
1
 
none 
0
 
0
 
S_SPAWNSTATE
  
S_GOLDBOX_OFF1
 
XLTV
 
B
 
89
 
A_GoldMonitorPop 
0
 
0
 
S_GOLDBOX_OFF2
  
S_GOLDBOX_OFF2
 
XLTV
 
C
 
4
 
A_PlayAttackSound 
0
 
0
 
S_GOLDBOX_OFF3
  
S_GOLDBOX_OFF3
 
XLTV
 
D
 
4
 
none 
0
 
0
 
S_GOLDBOX_OFF4
  
S_GOLDBOX_OFF4
 
XLTV
 
E
 
4
 
none 
0
 
0
 
S_GOLDBOX_OFF5
  
S_GOLDBOX_OFF5
 
XLTV
 
F
 
2
 
none 
0
 
0
 
S_GOLDBOX_OFF6
  
S_GOLDBOX_OFF6
 
XLTV
 
G
 
2
 
none 
0
 
0
 
S_GOLDBOX_OFF7
  
S_GOLDBOX_OFF7
 
XLTV
 
G
 
0
 
A_GoldMonitorRestore 
0
 
0
 
S_SPAWNSTATE
  
 
  Object type  info –  MT_INVCICO 
 
  
Thing type number 
none 
PINVB0  
  
Object type 
MT_INVCICO
 
  
Sprite name prefix 
PINV
 
  
SpawnState
 
S_PINV2
 
  
SeeState
 
S_NULL
 
  
SeeSound
 
sfx_None
 
  
AttackSound
 
sfx_None
 
  
PainState
 
S_NULL
 
  
PainSound
 
sfx_None
 
  
MeleeState
 
S_NULL
 
  
MissileState
 
S_NULL
 
  
DeathState
 
S_NULL
 
  
XDeathState
 
S_NULL
 
  
DeathSound
 
sfx_None
 
  
ActiveSound
 
sfx_None
 
  
RaiseState
 
S_NULL
 
  
SpawnHealth
 
1
 
  
ReactionTime
 
8
 
  
PainChance
 
0
 
  
Speed
 
2*FRACUNIT
 
  
Radius
 
8*FRACUNIT
 
  
Height
 
14*FRACUNIT
 
  
Display offset
 
0
 
  
Mass
 
100
 
  
Damage
 
62*FRACUNIT
 
  
Flags 
MF_NOBLOCKMAP|MF_NOCLIP|MF_SCENERY|MF_NOGRAVITY|MF_BOXICON
 
  
States – MT_INVCICO
  
State
 
Sprite prefix
 
Frame
 
Duration (tics)
 
Action 
Var 1
 
Var 2
 
Next state
 
Full brightness?
 
Translucency
  
S_PINV2
 
PINV
 
B
 
4
 
A_MonitorPop 
0
 
0
 
S_PINV3
 
No
 
0%
  
S_PINV3
 
PINV
 
C
 
4
 
none 
0
 
0
 
S_PINV4
 
No
 
0%
  
S_PINV4
 
PINV
 
D
 
4
 
none 
0
 
0
 
S_PINV5
 
No
 
0%
  
S_PINV5
 
PINV
 
E
 
4
 
none 
0
 
0
 
S_PINV6
 
No
 
0%
  
S_PINV6
 
PINV
 
B
 
18
 
A_Invincibility 
0
 
0
 
S_NULL
 
No
 
0%
  
 
  Object type  info –  MT_IVSP 
 
  
Thing type number 
none 
IVSPF0  
  
Object type 
MT_IVSP
 
  
Sprite name prefix 
IVSP
 
  
SpawnState
 
S_IVSP
 
  
SeeState
 
S_NULL
 
  
SeeSound
 
sfx_None
 
  
AttackSound
 
sfx_None
 
  
PainState
 
S_NULL
 
  
PainSound
 
sfx_None
 
  
MeleeState
 
S_NULL
 
  
MissileState
 
S_NULL
 
  
DeathState
 
S_NULL
 
  
XDeathState
 
S_NULL
 
  
DeathSound
 
sfx_None
 
  
ActiveSound
 
sfx_None
 
  
RaiseState
 
S_NULL
 
  
SpawnHealth
 
1000
 
  
ReactionTime
 
8
 
  
PainChance
 
0
 
  
Speed
 
8
 
  
Radius
 
64*FRACUNIT
 
  
Height
 
64*FRACUNIT
 
  
Display offset
 
2
 
  
Mass
 
16
 
  
Damage
 
0
 
  
Flags 
MF_NOBLOCKMAP|MF_NOCLIP|MF_NOCLIPHEIGHT|MF_NOGRAVITY
 
  
States – MT_IVSP
  
State
 
Sprite prefix
 
Frame
 
Duration (tics)
 
Action 
Var 1
 
Var 2
 
Next state
 
Full brightness?
 
Translucency
 
Animated?
  
S_IVSP
 
IVSP
 
A
 
32
 
none 
31
 
1
 
S_NULL
 
No
 
0%
 
Yes