Your first effect

Build a "Hit" effect one track at a time: a camera kick, a shake, a red flash and a sound. Each step adds one track, so you can play it after every step and see what changed.

You're at the deepest level. This page builds tracks by hand from primitives and drivers. The same effect fits in four lines with ready-made tracks, and the Effect builder shows how each one maps to what you'll write here. Going this deep is what lets you customise everything.

Setup

In a LocalScript, require MotionFX and grab the driver library. Add --!strict at the top so the editor checks your tracks and autocompletes names as you type.

--!strict
local ReplicatedStorage = game:GetService("ReplicatedStorage")

local MotionFX = require(ReplicatedStorage.MotionFX)
local Types = require(ReplicatedStorage.MotionFX.Types)
local FX, Drive = MotionFX.Enum, MotionFX.Drive

1. A kick

An effect is a list of tracks, and a track is one primitive (what changes) driven by one driver (how it changes over time). Start with a single Rotation track: a spring that pitches the camera up 4 degrees and lets it settle back.

MotionFX:Create("Hit", {
	Tracks = {
		{ Primitive = "Rotation", Driver = Drive.Spring({ Kick = Vector3.new(4, 0, 0), Frequency = 7, Damping = 0.45 }) },
	},
})

MotionFX:Play("Hit")

You don't need to stop it. A spring ends once it has settled, and the effect ends with its longest track.

2. A shake

Add a second Rotation track. Tracks on the same primitive add up, so the shake plays on top of the kick. Noise on its own would shake forever, so Modulate multiplies it by an envelope that starts at full strength and fades out over 0.6 s.

local hitEnvelope = Drive.Envelope({ Attack = 0.03, Release = 0.6 })

-- add to Tracks
{
	Primitive = "Rotation",
	Driver = Drive.Modulate(Drive.Noise({ Frequency = 16, Amplitude = Vector3.new(1, 1, 2) }), hitEnvelope),
},

3. A red flash

A Vignette track takes a number for a black edge, or a VignetteLayer for colour. Map reshapes the same envelope into a red layer, so the flash fades exactly as the shake does. The : Types.VignetteLayer annotation tells strict mode what the function returns.

-- add to Tracks
{
	Primitive = "Vignette",
	Driver = Drive.Map(hitEnvelope, function(amount: number): Types.VignetteLayer
		return { Intensity = amount * 0.6, Color = Color3.fromRGB(150, 0, 0) }
	end),
},

4. A sound

Sound tracks take no driver. They play their SoundId once and follow the effect's intensity. MotionFX.Sounds has the preset sounds, and you can pass any asset id.

-- add to Tracks
{ Primitive = "Sound", SoundId = MotionFX.Sounds.Shake, Volume = 0.8 },

5. Play and control it

Play returns a handle for that one playthrough. Scale it with Intensity, react when it finishes, or stop it early.

local handle = MotionFX:Play("Hit", { Intensity = 0.7 })

handle.Finished:Once(function()
	print("Hit finished")
end)

Some drivers never end on their own: Constant, Noise, Bind and Cycle, and looped sounds. An effect that uses one runs until you stop it:

local grade = MotionFX:Apply("Color", Drive.Constant({ Saturation = -0.6 }), { FadeIn = 0.3 })
-- later
grade:Stop(0.5)

The whole effect

local hitEnvelope = Drive.Envelope({ Attack = 0.03, Release = 0.6 })

MotionFX:Create("Hit", {
	Tracks = {
		{ Primitive = "Rotation", Driver = Drive.Spring({ Kick = Vector3.new(4, 0, 0), Frequency = 7, Damping = 0.45 }) },
		{
			Primitive = "Rotation",
			Driver = Drive.Modulate(Drive.Noise({ Frequency = 16, Amplitude = Vector3.new(1, 1, 2) }), hitEnvelope),
		},
		{
			Primitive = "Vignette",
			Driver = Drive.Map(hitEnvelope, function(amount: number): Types.VignetteLayer
				return { Intensity = amount * 0.6, Color = Color3.fromRGB(150, 0, 0) }
			end),
		},
		{ Primitive = "Sound", SoundId = MotionFX.Sounds.Shake, Volume = 0.8 },
	},
})

MotionFX:Play("Hit", { Intensity = 0.7 })

From here, see Retrigger policies for what happens when it's played again while running, and Examples for bigger effects.

Common mistakes