Environment effect

From Guild Wars Wiki

Environment effects are a type of skill that is activated by walking over a certain terrain, being within a certain location, holding a bundle item, activating an interactive object or even standing near certain NPCs. But all of them have something in common, and it's that all of them depend on the area you are in (such as the The Dragon's Lair mission), players cannot learn them or even temporily acquire them (unlike, for example, celestial skills) and they are never in the skill bar of any creature.

In the effects monitor, found in the top left corner by default, environment effects have a green border effect similar to other skills such as shouts, weapon spells or stances, but cannot be removed or prevented except by avoiding the action that triggers it, for example, leaving the area, dropping the bundle, etc.