The book closes the paradigm with explanations for individual changes. The essential relationships are:
FormRelevant changeResult
وَقَىfinal yāʾ changes to alifوَقَى
وَقَوْاweak ending adjusts before plural suffixوَقَوْا
يَقِيinitial root wāw disappearsيَقِي
لَمْ يَقِjussive removes final yāʾلَمْ يَقِ
قِremove imperfect prefix in imperativeقِ
وَاقٍindefinite defective noun loses final yāʾوَاقٍ
These are targeted explanations, not a claim that one rule handles all forms. Perfect, imperfect, imperative and active participle each have their own structure.