How to pick a random magic from a table?[Not Sloved]

Hello there im having problems picking a random magic from a table using math.random. Youtube wont help me so i want to ask u guys for help.

function OnPlayerAdded(Player)
Player:WaitForDataReady()
Player = game.Players.LocalPlayer
	Magic = Instance.new("StringValue", Player)
	Magic.Name = "Magic"
	if Player:LoadString("Magic") ~= "" then
		Magic.Value = Player:LoadString("Magic")
	else
		Elements = {"Water", "Fire", "Earth"}
		i = math.random(1, #Elements)
		Player.Magic.Value = Elements[i]
		Player:SaveString("Magic" , Player.Magic.Value)
		M = Instance.new("Message", workspace)
		M.Text = Magic.Value
		game.Debris:AddItem(M, 5)
	end
	if Player.Magic.Value == "Fire" then
		x = game.Lighting.Fireball:clone()
	elseif Player.Magic.Value == "Water" then
		x = game.Lighting.Waterball:clone()
	elseif Player.Magic.Value == "Earth" then
		x = game.Lighting.Rockball:clone()
	end
	x.Parent = Player.Backpack
end

game.Players.PlayerAdded:connect(OnPlayerAdded)
		
	
	
	
	

Assuming you have this as a Script, you don't need the third line as you can't access the LocalPlayer from a server script. Plus, you wouldn't need to use the LocalPlayer anyway as you're already getting the player from the PlayerAdded event.

Another reason you shouldn't use a LocalScript for you code is because LocalScripts can't handle data persistence saving and loading as it is server sided. I would also make your variables in the function local as variables can conflict if a new player enters.

Also, I believe WaitForDataReady is broken, so I took it out of your script.

The final script is below:

Elements = {"Water", "Fire", "Earth"} --Have Elements outside the script for ease.

function OnPlayerAdded(Player)
    local Magic = Instance.new("StringValue", Player)
    Magic.Name = "Magic"
    if Player:LoadString("Magic") ~= "" then
        Magic.Value = Player:LoadString("Magic")
    else
        local elem = math.random(1, #Elements) --I recommend you use local variables so that variables don't conflict.
        Magic.Value = Elements[elem]
        Player:SaveString("Magic" , Magic.Value)
        M = Instance.new("Message", Player.PlayerGui) --Put message in PlayerGui so that only the player can see it.
        M.Text = Magic.Value
        game.Debris:AddItem(M, 5)
    end
    if Magic.Value == "Fire" then
        local x = game.Lighting.Fireball:Clone()
	x.Parent = Player.Backpack
    elseif Magic.Value == "Water" then
       local  x = game.Lighting.Waterball:Clone()
	x.Parent = Player.Backpack
    elseif Magic.Value == "Earth" then
        local x = game.Lighting.Rockball:Clone()
	x.Parent = Player.Backpack
    end
end

game.Players.PlayerAdded:connect(OnPlayerAdded)

I would suggest using DataStores for your data saving/loading as Data Persistence is quite old now.

I hope my answer helps you. If it did, be sure to accept it.