ship-guardian-threshold ship-guardian-threshold Same as ship-guardian, except the lowest possible hull value is specified by the sexp rather than defaulting to 1. Call with a threshold of 0 (or use ship-no-guardian) to deactivate. Takes 2 or more arguments... 1: Threshold value. 2+: Name of ships to make unkillable.
There are two main uses of this SEXP over ship-guardian. First, it can be used to make ships appear less artificially-kept-alive by having their health stop dropping at an earlier (or even random) point. Second, some ships are capable of dealing so much damage that they can destroy a ship under standard guardian before it can kick in, which can be averted by having guardian protection kick in earlier.