Bigback monster

local monster = Instance.new("Model")
monster.Name = "Monster"
monster.Parent = workspace

local head = Instance.new("Part")
head.Name = "Head"
head.Shape = Enum.PartType.Ball
head.Size = Vector3.new(3, 3, 3)
head.Anchored = false
head.Parent = monster

local torso = Instance.new("Part")
torso.Name = "Torso"
torso.Size = Vector3.new(4, 5, 2)
torso.Anchored = false
torso.Parent = monster
torso.CFrame = CFrame.new(0, -3, 0)

local leftArm = Instance.new("Part")
leftArm.Name = "LeftArm"
leftArm.Size = Vector3.new(1, 4, 1)
leftArm.Anchored = false
leftArm.Parent = monster
leftArm.CFrame = CFrame.new(2.5, -1, 0)

local rightArm = Instance.new("Part")
rightArm.Name = "RightArm"
rightArm.Size = Vector3.new(1, 4, 1)
rightArm.Anchored = false
rightArm.Parent = monster
rightArm.CFrame = CFrame.new(-2.5, -1, 0)

local leftLeg = Instance.new("Part")
leftLeg.Name = "LeftLeg"
leftLeg.Size = Vector3.new(1, 4, 1)
leftLeg.Anchored = false
leftLeg.Parent = monster
leftLeg.CFrame = CFrame.new(1, -7, 0)

local rightLeg = Instance.new("Part")
rightLeg.Name = "RightLeg"
rightLeg.Size = Vector3.new(1, 4, 1)
rightLeg.Anchored = false
rightLeg.Parent = monster
rightLeg.CFrame = CFrame.new(-1, -7, 0)

local headMesh = Instance.new("SpecialMesh")
headMesh.MeshType = Enum.MeshType.Sphere
headMesh.Parent = head

local torsoMesh = Instance.new("SpecialMesh")
torsoMesh.Parent = torso

local leftArmMesh = Instance.new("SpecialMesh")
leftArmMesh.Parent = leftArm

local rightArmMesh = Instance.new("SpecialMesh")
rightArmMesh.Parent = rightArm

local leftLegMesh = Instance.new("SpecialMesh")
leftLegMesh.Parent = leftLeg

local rightLegMesh = Instance.new("SpecialMesh")
rightLegMesh.Parent = rightLeg

local humanoid = Instance.new("Humanoid")
humanoid.Parent = monster
humanoid.Health = 100

local rootPart = Instance.new("Part")
rootPart.Name = "HumanoidRootPart"
rootPart.Size = Vector3.new(2, 2, 2)
rootPart.Anchored = false
rootPart.Parent = monster
rootPart.CFrame = CFrame.new(0, -5, 0)

local rootWeld = Instance.new("WeldConstraint")
rootWeld.Part0 = rootPart
rootWeld.Part1 = torso
rootWeld.Parent = rootPart

local headWeld = Instance.new("WeldConstraint")
headWeld.Part0 = torso
headWeld.Part1 = head
headWeld.Parent = torso

local leftArmWeld = Instance.new("WeldConstraint")
leftArmWeld.Part0 = torso
leftArmWeld.Part1 = leftArm
leftArmWeld.Parent = torso

local rightArmWeld = Instance.new("WeldConstraint")
rightArmWeld.Part0 = torso
rightArmWeld.Part1 = rightArm
rightArmWeld.Parent = torso

local leftLegWeld = Instance.new("WeldConstraint")
leftLegWeld.Part0 = rootPart
leftLegWeld.Part1 = leftLeg
leftLegWeld.Parent = rootPart

local rightLegWeld = Instance.new("WeldConstraint")
rightLegWeld.Part0 = rootPart
rightLegWeld.Part1 = rightLeg
rightLegWeld.Parent = rootPart

local function onTouched(part)
    if part.Parent:FindFirstChild("Humanoid") then
        part.Parent:FindFirstChild("Humanoid"):TakeDamage(20)
    end
end

torso.Touched:Connect(onTouched)
leftArm.Touched:Connect(onTouched)
rightArm.Touched:Connect(onTouched)
leftLeg.Touched:Connect(onTouched)
rightLeg.Touched:Connect(onTouched)

local function animate()
    while true do
        task.wait(0.1)
        local randomX = math.random(-5, 5)
        local randomZ = math.random(-5, 5)
        monster:PivotTo(monster:GetPivot() * CFrame.new(randomX/10, 0, randomZ/10))
    end
end

task.spawn(animate)