The phrase "a good mastery of" is correct and usable in written English.
It can be used when discussing someone's proficiency or skill level in a particular subject or area.
Example: "To excel in this field, you need a good mastery of the fundamental concepts and techniques."
Alternatives: "a strong command of" or "a solid understanding of".
Coöperation in complex situations would require software with a good mastery of language to communicate with other players, something that doesn't trouble software taking on Go or Starcraft.
Majors are expected to have a good mastery of an East Asian language, and focus on a particular sub-region or a substantive issue involving the region as a whole.
It is based on a good mastery of the definitions and recommendations on this subject.
With increasing demand for digital arts, illustrators who have a good mastery of both artistic skills and computer techniques will be in demand.
Bearing the "for glary of the motherland" and "proving ourselves that we can do others are able to do" in minds, all the participants have a good mastery of all required skills after intensive and strict training in a short time.
In fact, the understanding of biological evolution requires not only basic scientific knowledge about the organization of living beings but also a good mastery of the concept of species, classification criteria, principles of genetics, and also of the nature of science, as noted by Nadelson (2009).
Most of the participants have a fairly good mastery of ICT.
Most participants have a fairly good mastery of ICT, although good practices about their use remain insufficiently known.
You have pretty good mastery of it and it gives you this feeling of efficacy.
These problems are usually solved after the learning curve is complete and good mastery of the "mobile window" concept is achieved [8].
The absence of a curative therapy pushes caregivers, non-drug interventions and medical social services to the forefront, which requires that health professionals have good mastery of local resources to guide the patient and his/her entourage [ 3, 4].
