Mapudungun is an endangered Araucanian language that possesses a very productive frustrative suffix (-fu-). As with other frustratives across languages, -fu- is used to express the non-realization of an expected outcome or state, as well as counterfactuality. When combined with modals, the suffix brings about various semantic shifts, such as (i) strong to weak necessity, (ii) attainable to unattainable desires, and (iii) actual to counterfactual desires and obligations. The attested range of meanings strongly suggests that Mapudungun behaves like so-called transparent ought/wish languages. The focus of this chapter is on overcoming the methodological challenges posed to the researcher when eliciting primary data related to these phenomena. More constructively, I provide a basic guideline for producing controlled scenarios that can be used as the basic content of appropriate discourse contexts. I show that the task can be greatly simplified by mapping the modal territory with the following circumstantial parameters: achieved/unachieved, compulsory/advisory, attainable/unattainable, and actual/counterfactual.