induration. 1. the process of hardening or being hardened.
1 They're weak against the Ice and Water types in reference of erosion, which cause this elements to the ground. 2  They're immune against the Electric type because in real life, the ground is a natural sink of electrons.  The Bug type resists them because many bugs like worms live inside the ground and many of them eat it.
Deadly force is justified in defense of one's property by a person who is privileged to be on the premises and who reasonably believes such force is necessary to prevent an attempt by the criminal trespasser to commit any crime of violence. Twenty states have stand-your-ground laws. Generally, these laws allow an individual to use force in self-defense when there is reasonable belief of a threat, without an obligation to retreat first if the individual (1) has a legal right to be at the location and (2) is not engaged in an unlawful activity.