Torpor Orb and Etched Monstrosity don't interact the way you're thinking they do. Torpor Orb will stop enter the battlefield abilities that trigger, however, Etched Monstrosity 's ability does not trigger.
603.1. Triggered abilities have a trigger condition and an effect. They are written as [Trigger condition], [effect], and begin with the word when, whenever, or at. They can also be expressed as [When/Whenever/At] [trigger event], [effect].