Arc k

local function arc(Start,Finish,Height)
    Height=Height or (Start.p-Finish.p).magnitude/10;
    local cLerp=function(a,b,i)
        return a:lerp(b,i)+Vector3.new(0,math.sin(i*3)*Height,0);
    end;
    for i=0,1,.05 do
        local old,new;new=cLerp(Start.p,Finish.p,i+.05);old=cLerp(Start.p,Finish.p,i);
        local real=CFrame.new(old,new);
        local dist=(old-new).magnitude;
        local line=Instance.new'Part';
            line.Anchored,line.FormFactor,line.Size,line.CFrame,line.Parent=true,'Custom',Vector3.new(0,0,dist),CFrame.new(old,new)*CFrame.new(0,0,-dist/2),workspace;
    end;
end;
arc(CFrame.new(0,5,0),CFrame.new(0,5,-25),15);--