The following is a good way to save valuable units, for example, if you were trying to save a Spartan or The Prophet of Regret. This works especially well with the Covenant Base (Prophet of Regret). When you officially make the Prophet or a Special Elite unit, make them stand exactly where they spawned from in the base. Next, select the base and choose "Lock". The Claws will interlock with each other, trapping your character in there. He will stay safe from enemy fire, but if an enemy gets within range, he will go out and fire. Then you will just have to put your character back in there. Note: You will have to keep enemies at bay so he will not go out. It still saves money and time.