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.
Freebase (0.00 / 0 votes) Rate this definition: Median lethal dose. In toxicology, the median lethal dose, LD50, LC50 or LCt50 of a toxin, radiation, or pathogen is the dose required to kill half the members of a tested population after a specified test duration.LD50 figures are frequently used as a general indicator of a substance's acute toxicity.n toxicology, the median lethal dose, LD50, LC50 or LCt50 of a toxin, radiation, or pathogen is the dose required to kill half the members of a tested population after a specified test duration. LD50 figures are frequently used as a general indicator of a substance's acute toxicity.