Another question, How can I make my projectile script won't hurt the caster?

Since I am making a 2-in-1 game (minigame and magic fighting), I am making magics but I don't like the caster being hurt from their own projectile?

So I can't see your code but I'm guessing it works like this.

if Hit and Hit.Parent then
if Hit.Parent:FindFirstChild("Humanoid")  then
Hit.Parent.Humanoid:TakeDamage(25)
end
end

all you need to do is add another condition to it like

if Hit and Hit.Parent and Hit.Parent ~= game.Players.LocalPlayer.Character then
if Hit.Parent:FindFirstChild("Humanoid")  then
Hit.Parent.Humanoid:TakeDamage(25)
end
end