(intermediate) Script Half-way works, but nothing happens at the end. No out put errors?

As the post above me said, you've got a loop that won't let your script continue. Therefore, you're going to need to force the script to run two things at once. Scary, I know. This is when we can use the Spawn() function, which you can read more about here.

local h = script.Parent.Humanoid

function onDeath()
    if h.Health then
        if h.Health == 0 then
        game.Lighting.SuperEvilKeycard:Clone().Parent = game.Players.LocalPlayer.Backpack
        script.Parent:Destroy()
        end
    end
end

spawn(function(onDeath))

while true do
    h:MoveTo(workspace.DontClean1.Position)
    wait(5)
    h:MoveTo(workspace.DontClean2.Position)
    wait(5)
end

If this helped you out, consider accepting this answer. If not, let me know and I'll be sure to help you out further.