Immunity

Immunity represents a total Immunity to Damage of a specific damage type (such as piercing, weapon, caustic, or holy) or specific keyword. When a creature is subject to damage which it is immune to, or is the target of an attack or ability with a keyword they are immune to, the attack or ability has no effect. Immunity can be natural or the result of a power or similar ability.

While nothing can overcome Immunity, some abilities may be able to strip magical immunity that is not innate to a creature (i.e. it is possible to strip immunity resulting from a power or similar effect, but not immunity that is innate to a creature's being).

If you are subject to an effect that deals multiple damage types, you must have Immunity to both damage types to gain the benefit.