Fire Ball Script Not Damage Humanoid?

Your code

Friaza's tutorial is very useful to get someone use to KeyDown() functions, and the code you have is ALMOST perfect, however, some parts of your code aren't exactly perfect. For the code to work, you need two scripts: a local script and a regular script. Name the local script 'Fireball' and name the script 'Firedamage' (Have Firedamage INSIDE Fireball, and have the code be a child of StarterPack). Now, in the Firedamage code, put this edited code into it (I'll explain the code to the best of my ability...)

Firedamage Code

function onDamage(Part)--function to cause damage to those hit with fireball

    if Part.Parent:FindFirstChild("Humanoid") ~=nil and Part.Parent.Name ~= "script.Parent.Name" then--If the thing is humanoid then

        script.Disabled = true

        local f = Instance.new('Fire', Part)

        for i = 1,25 do--Does damage all the way to 25

            f.Size = f.Size +0.25--

            Part.Parent.Humanoid.Health = Part.Parent.Humanoid.Health -1--Declines health -1

        wait (0.05)

        end--end the first argument of code chunk

        f:remove()

        Part.Parent.Humanoid.PlatformStand = true

        script.Parent:remove()--Removes the action

    end--end the second argument of code chunk

end--end the thrid argument of code chunk

script.Parent.Touched:connect(onDamage)

Now, in the Fireball code, you need to put this edited code into it (again, I'll explain to the best of my ability...)

Fireball code

--Variables
Player = script.Parent.Parent--To get to Player

mouse = Player:GetMouse()--Gets the mouse function

--function

function onKeyDown(key)--The function

    local Key = key:lower()--Key pressed sequence

    if key =='z' then--The player hits 'z'

        local x = Instance.new('Part', workspace)--Creates a new part

        x.BrickColor = BrickColor.new("Bright red")--Fire is red...

        x.Size = Vector3.new(10, 10, 10)--Makes the fire ball look like an actuall fire ball

        x.TopSurface = 'Smooth'--Removes the studs to make it look more realistic

        x.BottomSurface = 'Smooth'--Removes the studs to make it look more realistic

        x.Shape = 'Ball'--It is a fire ball...

        x.Name = Player.Name--this makes it so that way the fireball doesn't hurt the player using it

        x.CanCollide = false

        x.Transparency = 0.7--Make it look more realistic

        local fd = script.Firedamage:Clone()--Clones the fire damage for future use as well

        fd.Parent = x--makes firedamage apart of the fireball

        local y = Instance.new('BodyVelocity', x)

        y.maxForce = Vector3.new(math.huge, math.huge, math.huge)--Makes the fireball not too huge, but not too small

        y.velocity = Player.Character.Torso.CFrame.lookVector*80--Allows it to be shot from the Player's torso

        local f = Instance.new('Fire', x)--Adds fire to the new part

        f.Size = 15--Fire will be size 15

        f.Heat = 0--No heat since it'll make fireball look weird

        x.CFrame = Player.Character.Torso.CFrame*CFrame.new(0, 0, -12)--Allows it to be shot from your character, offically...

        fd.Disabled = false

        game.Debris:AddItem(x, 1)--Removes the fire ball all together

        print ('Fireball successfully worked!')

    end--end the first argument of code chunk

end--end the second argument of code chunk

mouse.KeyDown:connect(onKeyDown)--Repeats function for it to be confirmed to work

In conclusion...

Your code was right, but I have some edits to it to have it cleaner. Let me know if it doesn't work.

Greek