1 702.12b A permanent with indestructible canât be destroyed. 2  Such permanents arenât destroyed by lethal damage, and they ignore the state-based action that checks for lethal damage (see rule 704.5g). 3  702.12c Multiple instances of indestructible on the same permanent are redundant.
lethal dose. n. (Pharmacology) the amount of a drug or other agent that if administered to an animal or human will prove fatal.
Referring to a common salt of fluoride, sodium fluoride (NaF), the lethal dose for most adult humans is estimated at 5 to 10 g (which is equivalent to 32 to 64 mg/kg elemental fluoride/kg body weight).