No, it's a new wave. Tower defense. HELP!

Repeat will timeout if it takes too long. Instead, try to use use

while task.wait() do
  if #workspace.Mobs:GetChildren() <= 0 then
   break;
  end
end

Loops don’t do that, they repeat until a condition is met or they break (either by Server timeout of by force)

plus, it wont take long either, so this wouldnt do anything

So, what do we do then? Ah, here offer scripts, and you say that they do not work, then what to use?