How do you fix this collision for a model? (Model/Bullet or Ball to Model/Boss character)

.Touched is not a very effective way to detect collisions; as stated in a devforum post: you can use BasePart:GetTouchingParts or Region3 for most effective detection. Region3 is a specific region of space, it's parameters are as follows:

local Reg3 = Region3.new(Vector3.new(0,0,0), Vector3.new(0,0,0))

Region3 looks at a specific area of space in workspace.

:GetTouchingParts() shows what parts are touching that exact area/object. It returns a table. Like so:

local obj = workspace.Part
local obj2 = workspace.Part2
while true do
    wait()
    local a = obj2:GetTouchingParts
    if table.find(a, obj) then
        print("TOUCHING!")
        break
    end
end

NB - I would not recommend using Region3 for this. You should just use obj:GetTouchingParts().

Hey WoofWoofWatermelonYT,

As far as I can see from your code the reason why .Touched isn't working is that you're for loop will only run once. Maybe try adding a while true do to your code like so:

while true do
for i, v in pairs(script.Parent:GetChildren()) do
    if v:IsA("Part") then
        v.Touched:Connect(function(hit)
            if hit.Name == "Waterball" then
                script.Parent.Damage.Value = script.Parent.Damage.Value - 100
                script.Parent.Head.BillboardGui.TextLabel.Text = "Damage Remaining: " .. tostring(script.Parent.Damage.Value)
            end
        end)
    end
end
wait()
end

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Any questions? Feel free to contact me.

Cheers,

Orcazate