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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/ikeepcalm/coi-client/llms.txt

Use this file to discover all available pages before exploring further.

This page is the complete parameter reference for all 10 COI Client screen-space visual effects. Each effect is triggered by sending the coi-client:effect plugin messaging payload from your Paper plugin — see Triggering Effects for the integration setup. Params are passed as a comma-separated key=value string; any param you omit falls back to the default listed below.
Darkens the edges of the player’s screen, drawing the eye toward the center. A simple but effective mood setter. Good for: cursed zones, low sanity, death proximity.
​
intensity
float (0–1)
default:"0.7"
Controls the darkness and how far inward the vignette reaches toward the screen center. Higher values create a more claustrophobic feel.
​
duration
long (ms)
default:"-1"
How long the effect runs in milliseconds. -1 means persistent — the effect stays active until explicitly stopped with sendEffect(player, "vignette", "stop"). The effect fades out gracefully over the last 500ms before expiry.
// Mild vignette for a cursed zone entrance — 10 seconds
sendEffect(player, "vignette", "intensity=0.5,duration=10000");

// Strong persistent vignette for low sanity
sendEffect(player, "vignette", "intensity=0.8");

// Maximum persistent vignette — extreme darkness
sendEffect(player, "vignette", "intensity=1.0");
A vignette that pulses with a realistic lub-DUB cardiac rhythm. The screen darkens at the edges on each beat, creating a visceral sense of a racing or labored heart. Good for: high tension, near-death, possessed states.
heartbeat is suppressed when the player has Epilepsy Mode enabled in COI Client settings.
​
intensity
float (0–1)
default:"0.85"
Peak darkness of the vignette at the top of each beat pulse.
​
bpm
float
default:"75"
Beats per minute. The lub-DUB rhythm is fully synchronized to this value. Higher BPM creates urgency; lower BPM creates a slow, ominous dread.
​
duration
long (ms)
default:"-1"
How long to run. Persistent by default. Fades out over the last 600ms before expiry.
// Resting dread — slow ominous pulse
sendEffect(player, "heartbeat", "intensity=0.7,bpm=50");

// High tension — fast and heavy
sendEffect(player, "heartbeat", "intensity=0.9,bpm=100,duration=15000");

// Near-death — maximum intensity, elevated BPM
sendEffect(player, "heartbeat", "intensity=1.0,bpm=110");
Branching fracture lines grow inward from all eight screen origins (four corners and four edge midpoints) toward the center. At high intensity the cracks visibly pulse red. Good for: reality breaking, maximum madness, catastrophic events.
Crack geometry is generated once on first render, seeded by the trigger timestamp — each call to sendEffect produces a unique fracture pattern.
​
intensity
float (0–1)
default:"0.7"
Controls how far the cracks extend toward the screen center and the overall density of branches.
​
pulse
boolean
default:"false"
When true, the cracks glow and pulse red rhythmically, suggesting a living wound in reality.
​
duration
long (ms)
default:"-1"
How long the cracks persist. Persistent by default.
// Subtle corner cracks only
sendEffect(player, "cracks", "intensity=0.4");

// Heavy cracks with red pulse — timed 8 seconds
sendEffect(player, "cracks", "intensity=0.8,pulse=true,duration=8000");

// Maximum persistent cracks
sendEffect(player, "cracks", "intensity=1.0,pulse=true");
Creepy eyes emerge from the darkness of the screen, open to stare at the player, then slowly close and fade away. Eyes are distributed across the screen in a grid (up to 3 columns). Good for: being watched, high madness, cursed locations.Timing breakdown per eye (eyes are slightly staggered from each other):
PhaseTimingDescription
Ambient glow0–500msA dark halo fades in around each eye
Opening500–2000msEyelids slowly open
Staring2000ms–(duration−2500ms)Eyes hold open and stare
ClosingLast 2000msEyelids close and fade out
​
count
int
default:"2"
Number of eyes to show. Values from 1 to 6 are recommended. Eyes are distributed evenly across the screen.
​
duration
long (ms)
default:"8000"
Total lifetime of the effect including all animation phases. Must be at least 4500ms to allow the open and close animations to complete properly.
// Single eye — brief, unsettling
sendEffect(player, "eyes", "count=1,duration=6000");

// Four eyes staring for a long time
sendEffect(player, "eyes", "count=4,duration=14000");

// Six eyes — maximum dread, default 8 seconds
sendEffect(player, "eyes", "count=6");
VHS-style horizontal distortion lines that strobe in short bursts, then cut out, then burst again. Lines flicker at approximately 12 times per second rather than every frame, creating an authentic analog corruption look. Good for: teleportation, reality corruption, spell side-effects.
glitch is suppressed when the player has Epilepsy Mode enabled in COI Client settings.
Line types (randomly mixed each burst):
  • Dark horizontal scan band
  • White flash band
  • RGB chromatic fringe (red line above, cyan line below)
  • Horizontal split block (offset on one half of the screen)
​
intensity
float (0–1)
default:"0.7"
Controls the number of lines per burst (3–8), their alpha, and how frequently bursts occur. At intensities above 0.85, an occasional full-screen bright flash can also appear.
​
duration
long (ms)
default:"3000"
How long the glitch runs. Defaults to auto-expiring after 3 seconds — unlike most effects, glitch is finite by default.
// Quick flicker on teleport
sendEffect(player, "glitch", "intensity=0.5,duration=1500");

// Heavy sustained corruption
sendEffect(player, "glitch", "intensity=1.0,duration=5000");

// Barely-visible single flicker
sendEffect(player, "glitch", "intensity=0.3,duration=500");
Dark red streaks fall down the screen like drops of blood, each with a randomized speed and opacity. Good for: combat encounters, rituals, curses, death proximity.
​
intensity
float (0–1)
default:"0.7"
Controls the number and density of falling drops across the screen.
​
duration
long (ms)
default:"-1"
How long the rain persists. Persistent by default.
// Light drizzle — timed 8 seconds
sendEffect(player, "bloodrain", "intensity=0.3,duration=8000");

// Moderate combat effect
sendEffect(player, "bloodrain", "intensity=0.6,duration=5000");

// Heavy persistent downpour
sendEffect(player, "bloodrain", "intensity=1.0");
Ice crystals grow inward from all screen edges accompanied by a blue-white icy gradient overlay. Combines branching crystal lines with cold-tinted corner fills. Good for: frozen spells, cold zones, ice pathway abilities.
​
intensity
float (0–1)
default:"0.7"
Controls how far the frost reaches inward and how bright the blue-white tint appears.
​
duration
long (ms)
default:"-1"
How long the frost persists. Persistent by default.
// Moderate frost for a cold zone — 10 seconds
sendEffect(player, "frost", "intensity=0.6,duration=10000");

// Heavy persistent frost — player is frozen solid
sendEffect(player, "frost", "intensity=1.0");

// Light frost tint — entering a chilly area
sendEffect(player, "frost", "intensity=0.3,duration=6000");
Cryptic text phrases fade in and out at random positions across the screen. The spawn rate scales with intensity. Custom phrases can be injected via the text param. Good for: high madness, haunted locations, Fool/Door pathways, forbidden knowledge.Default phrase pool:
“they can see you” · “don’t look back” · “it knows YOUR name” · “you should not be here” · “RUN” · “the door IS open” · “forget” · “help me” · “it’s behind you” · “turn around” · “not real” · “listen” · “almost” · “wrong PLACE” · “he is watching”
​
intensity
float (0–1)
default:"0.7"
Controls how frequently new phrases spawn on screen.
​
duration
long (ms)
default:"-1"
How long whispers appear. Persistent by default.
​
text
string (pipe-separated)
default:"built-in pool"
A |-separated list of custom phrases to show instead of the built-in pool. Spaces within a phrase are fine; only | is the delimiter.
// Default whispers at moderate intensity
sendEffect(player, "whispers", "intensity=0.5");

// Custom phrases for a ritual scene — timed 20 seconds
sendEffect(player, "whispers", "duration=20000,text=the rite begins|do not resist|it is too late");

// High madness — frenetic default whispers
sendEffect(player, "whispers", "intensity=0.9");
A circular vignette closes inward from all edges, leaving only a shrinking oval of visibility at the screen center. Rendered via scanline fill (approximately screenHeight ÷ 3 draw calls per frame). Good for: exhaustion, confusion, extreme madness, near-death.
Due to the scanline rendering approach (~screenHeight ÷ 3 draw calls per frame), tunnel is the most GPU-intensive effect. Avoid running it simultaneously with other heavy effects for extended durations.
​
intensity
float (0–1)
default:"0.7"
How far the tunnel closes inward. At 1.0 the visible window narrows to near-blackout.
​
duration
long (ms)
default:"6000"
Total lifetime of the effect. Defaults to auto-expiring after 6 seconds.
​
closeDuration
long (ms)
default:"2000"
Time taken to animate from fully open to the target intensity. The same value is also used for the fade-out at the end.
// Moderate tunnel — 8 seconds
sendEffect(player, "tunnel", "intensity=0.6,duration=8000");

// Dramatic slow close — near-death
sendEffect(player, "tunnel", "intensity=0.95,duration=5000,closeDuration=3000");

// Quick flutter — disorientation spike
sendEffect(player, "tunnel", "intensity=0.4,duration=3000,closeDuration=500");
An instant full-screen color wash that rises quickly (first 15% of duration) then fades out smoothly for the remainder. Only 1 fill call per frame — extremely lightweight. Good for: ability activation feedback, pathway-colored casts, heals, explosions.
flash is suppressed when the player has Epilepsy Mode enabled in COI Client settings.
Pathway color reference:
PathwayHexPreview
Fool8B00FFPurple
Door0055FFBlue
SunFFDD00Yellow
Tyrant00CCCCCyan
DemonessFF2200Red
PriestFF8800Orange
​
color
hex RGB (no #)
default:"FFFFFF"
The color of the flash as a 6-character hex RGB string. Do not include the # prefix.
​
intensity
float (0–1)
default:"0.6"
Peak opacity of the flash at the top of the rise phase.
​
duration
long (ms)
default:"500"
Total time from flash start to full fade-out.
// Sun pathway ability cast — golden flash
sendEffect(player, "flash", "color=FFDD00,intensity=0.6,duration=300");

// Demoness red burst — aggressive ability
sendEffect(player, "flash", "color=FF2200,intensity=0.8,duration=400");

// Tyrant hit confirm — cyan
sendEffect(player, "flash", "color=00CCCC,intensity=0.5,duration=300");

// White heal flash
sendEffect(player, "flash", "color=FFFFFF,intensity=0.7,duration=600");

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